Network Configuration for a Wi-Fi Access Point

Network Configuration for a Wi-Fi Access Point

This page describes how to configure the network interfaces for a Raspbery Pi running as a Wi-Fi Access Point (AP). This is just one step in a larger list of instructions, which can be found on the page Raspberry Pi Wifi Access Point. The instructions here do not include the routing, which is covered later.

We need to configure two networks, the “local” network managed by hostapd to be a Wi-Fi Access Point (AP), and the “upstream” network connection to the Internet. The upstream network can be wired or Wi-Fi, and it could use a fixed IP address, or it could be a DHCP client, so there are lots of possible variations. We will use wlan0 for the Wi-Fi Access Point, since we will always have that on Wi-Fi, and use wlan1 if the upstream network connection is also via Wi-Fi.

Local Area Network (LAN) for the Access Point (AP)

The first Wi-Fi adapter, called wlan0, will be used for the Wi-Fi Access Point (the local network). It’s best to use the IP address range for a Private Network.1 For a small home network you can put the following (or something like it) in the file /etc/network/interface:

allow-hotplug wlan0
iface wlan0 inet static

This configuration is for a “Class C” network, which can have up to 254 IP addresses. For a large public event or venue you will probably want to use a class B or even a Class A network.2  In that case you can use the values in Table 1 to fill in the appropriate fields in the interfaces file.

Name Size address network netmask broadcast gateway
Class C 254
Class B 65,534
Class A 16,777,214

Table 1. Private Network settings for Class C, B, and A networks.  For more details on private networks see RFC 19183


Upstream Connection

There are several different ways to make the upstream connection.   It can be wired or Wi-Fi, and it could have a static IP address or it could get an address and other network settings from a DHCP server.


We will put the configuration for each interface in a separate file in the directory to make it easier to select which upstream interface to use, and also because it allows you to be a DHCP client on the upstream link.

(If you have a static or dhcp interface in /etc/network/interfaces then the dhcp client won’t start.4) If your access point won’t act as a DHCP client (it will definitely be a server, but that is different) then you can put all the configuration into the one file /etc/network/interfaces.

First, add the following to the top level file, /etc/network/interfaces:

# wlan0 is the Access Point

allow-hotplug eth0
allow-hotplug wlan1
# Now read full interface configuration from the subdirectory
source-directory /etc/network/interfaces.d

That last line is what reads the other files in that subdirectory. I have found that it is important to use allow-hotplog for wlan0 instead of auto; When I used auto then hostapd could not find wlan0, though it was up later when I checked. Maybe the boot order is different?



  • The upstream connection can be either via wired ethernet, on interface eth05 or via Wi-Fi, on interface wlan1. I will describe both and you can pick one or the other to connect to the Internet.  It’s even possible to have both upstream links enabled at the same time — in case one fails the other will still work. You have to decide if you use DHCP (as a client) or a static the IP address and netmask and gateway.


First, put the following in the file /etc/network/interface.d/wlan1 for the second wireless interface:

iface wlan1 inet static
  wpa-ssid "UpstreamSSID"
  wpa-psk "PassWordGoesHere"
  wpa-group TKIP CCMP
  wpa-key-mgmt WPA-PSK

Next, add the following to /etc/network/interface.d/eth0 for the wired upstream connection:

iface eth0 inet dhcp

These are just examples – you could use a static IP address for the wired interface, or use dhcp for the upstream WiFi connection. Having an entry for an interface that does not exist won’t cause problems.

Either way, we will come back to edit these files when we set up the routing tables, which
is describe in “Raspberry Pi Access Point Routing Tables.”

Notes and References

  2. Cisco Networking Academy > CCNP 1: Advanced IP Addressing Management > Private Addressing and NAT.
  3. RFC 1918: Address Allocation for Private Internets
  4. See the file /usr/lib/dhcpcd5/dhcpcd.
  5. It may have a different name if you have enabled “predictable” network interface names

COVID-19 Educational Technology Glossary

The novel (i.e. new) coronavirus, SARS-CoV-2, has prompted novel (i.e. new) terminology in the field of educational technology.  To keep track of it all, I’ve started this glossary page, which I will update from time to time.   I welcome additions, either in the comments or by email.  I am solely responsible for any mistakes or misconceptions.

COVID-19 – The disease caused by the virus now known as SARS-CoV-21

SARS-CoV-2 – The official name of the virus that causes COVID-19.2

Hybrid – A course which is partially taught in person and partially taught online (no other specification).3

Synchronous – literally “at the same time.”   A course which meets at a regularly scheduled time, whether it is in-person or online.

Synchronous online – a course which is strictly online and strictly synchronous.

Asynchronous – a course where activities are done on the student’s own schedule without specifically scheduled meetings.  The opposite of synchronous.

Asynchronous online – From Open SUNY:4100% of the direct instruction occurs under time delay; that is, direct instruction is recorded/stored and accessed later.”   In other words, this course is strictly online with no synchronous component.

Combined online – online instruction (only on-line) which is a mixture of synchronous and asynchronous instruction  (from Open SUNY Online Learning Definitions).   Some people might shorten this to just combined.

Blended – At SUNY New Paltz, at least, the term has been used to mean a course “that includes asynchronous and synchronous online elements.”5.   It might seem at first that this is another term for combined online, but note that combined online requires only on-line instruction, while this definition of blended does not, it only “includes” it.

Local+Remote – a hybrid course which is synchronous, with some students in the classroom and others joining remotely, all at the same time.  This could be a lecture class or a lab. (I coined this myself because nothing else covers this specific combination and I needed a term for it.)

Full Remote – a hybrid course where all students are outside of the classroom.  This could be synchronous or asynchronous.

Half-Remote – a hybrid course where half the students are in the classroom and half the students are remote.  This refers primarily to a synchronous course, in which case see Local+Remote above, but might be used for a class where the remote cohort works on assignments asynchronously.

Hyflex – According to OpenSUNY6  “Combines online and face-to-face instruction simultaneously into one single course section.  Students are able to participate in class in different ways: as asynchronous distance learner (via real-time, video- streaming); as an asynchronous distance learner (accessing materials, recorded lectures, and responding at a later time); as a face-to-face learner (physically present in the classroom); or as a flexible learner (with a degree of choice as to how they participate each week; sometimes face-to-face, sometimes by streaming class sessions, etc.). (New code as of Fall 2019)”  Official classification as a hyflex class requires strict certification that all modes are possible and supported, so don’t use this term unless the course is certified for hyflex.

Extended Virtual Learning (EVL) – essentially the same as Local+Remote (see above).   This first appeared in a chart distributed to the campus community on 10 August 2020 with the definition “A face-to-face class where, at the same time, some students attend in-person while others attend via a remote, synchronous web-conferencing session.”    In online course listings this is abbreviated as “EVL”.7

Split-Shifts – having half the class come during the first half of the period, and the other half of the class come during the second half of the period.  Or a third of the class coming in for a third of the scheduled time.   More appropriate for longer class meetings or labs.  Alternatively, the allocated time can be doubled and then half the class comes during one full period, and then the other half comes for another full period.

Every-Other – an arrangement where one part of the class attends in person on one day, while the other part of the class attends on another day.   For example, if the class has a room reserved on Tuesday and Thursday, then half the class comes in on Tuesday, and the other half comes in on Thursday.

Beak Peaker – a person who is wearing a mask, but their nose is peaking out over the top of it.8

Mask Slacker – a person who does not wear a mask (when they should?).  Originally used during the 1918 Spanish Flu pandemic (at least on the west coast9).

Covidiot – a person who engages in risky practices regarding COVID-19.  A portmanteau word from COVID-19 and idiot.10

Rat-Licker – From the Urban Dictionary:11 A person who refuses to wear a mask during an outbreak of an airborne virus such as Covid-19. (A reference to the idea of licking a rat during the bubonic plague).

References and Notes

Local+Remote Lab Classes

Local+Remote Lab Classes

This article explains a potential way to teach physics lab classes in the time of COVID-19, in a way that gives students some hands-on experience with the equipment and preserves the collaborative element of working as lab partners. (750 words)

Planning for teaching physics labs in the Fall of 2020 is fraught with difficulties.   One way we might teach labs is to use video conferencing software and extra webcams to allow students to work together to collect real data using real laboratory equipment, in what I refer to as a local+remote arrangement1  (this may also be referred to as EVL.2)  Here’s how it might work:

  1. The class would meet at the scheduled time, but with only half of the students in the classroom and the other half  joining via video. Each student would log in to Blackboard and join the class using Blackboard Collaborate Ultra.  The students in the classroom would use the existing laptops for this, which all have a camera and a microphone.  The instructor would also join the video meeting, even though they are in the room (or maybe they are not?)
  2. It’s often the case that the instructor provides the whole class some background information or special instructions at the beginning of the class.  Some of this could be provided via a video recording before class, but the instructor could also present to the entire class by using the document camera. The images from the document camera would be transmitted to the remote students via Blackboard, but could also be shown to the local students using the room projector system. Details on how to use the document camera this way are given here.
  3. When students are ready to begin the experiment, the instructor can assign them to “break-out rooms” in Blackboard, putting one local student and one remote student together as lab partners. The lab partners can see each other and talk to each other to collaborate, but each group is independent of the others.
  4. A webcam is attached to the laptop in the classroom, and the local student can point it at the equipment and share the video from the camera with the remote student. (See Figure 1.)  This would give the remote student a more complete experience of the exercise, even though they are not in the room. Sharing video from an external webcam in Blackboard Collaborate Ultra is just as easy as sharing the screen or sharing an application window.3

    Figure 1: Webcam pointed at a physics lab experiment, and shared via Blackboard Collaborate Ultra
  5. If students working together have a question they can use the “raise my hand” feature in Blackboard to get the attention of the instructor, who can then join their break-out room to help them. If the instructor can answer questions or give guidance via the video link then they do not even have to remain in the room.  The instructor could do this from their office or another room.  If something breaks, or if there is another reason the instructor has to be in the room, then they can assist the local student in person, but then leave the room (or return to the instructor station) when they are done.
  6. If data are saved in files (eg. from Logger Pro) then those data files can and should be shared with the remote student before the lab session is over.  (Ideally the instructor will remind the local student to do so before they leave the room.)  The students may need to be reminded that the computers erase any files saved on them when they reboot.

Notes and References

  1. The term “hybrid” means a course that has both-in person and remote components, but nothing more.  I have been using the term “local+remote” to mean a hybrid class which is synchronous (meets at a certain specified time) where some of the students are in the classroom while others join via the computer, all at the same time.
  2. In an official chart of teaching modalities distributed to our campus community in early August this is referred to as “Extended Virtual,” with the abbreviation “EVL” in on-line course lists.  I don’t like that this is likely to be pronounced “evil”.
  3. It’s also just as easy to share an extra camera in Zoom, except that the option is in the “Advanced” part of the Zoom sharing menu.  WebEx does not (yet?) offer the option of sharing an extra webcam, though you can switch your video to a different camera (which is not quite as good).

Potential Use of Steerable Consumer Home Cameras for “local+remote” Laboratory Instruction

Potential Use of Steerable Consumer Home Cameras for “local+remote” Laboratory Instruction

In this article I report what I’ve learned so far about the possibility of using steerable consumer home monitoring cameras (“nanny cams”) to allow students to work together on laboratory exercises, with one student in the room and one (or more?) participating using the video and audio from the camera.   (~4660 words)

Introduction and Motivation

The COVID-19 pandemic caused all instruction at SUNY New Paltz to move online in March 2020, including labs.  Introductory physics labs were performed by having faculty record videos showing the apparatus and the process of collecting of data, and then students analyzed the data and wrote lab reports. This lost a number of the benefits of student lab work, including both real-time interaction with the equipment and real-time interaction with other students.

Lab students work together as “lab partners” for a number of reasons. One is that equipment can be limited, especially if it is expensive.  Another is that some activities require more than one set of hands.  But even when these considerations don’t apply, it has long been recognized that working together with a lab partner is a valuable part of lab.  Getting an experiment to work requires problem solving and troubleshooting,1 and collaboration makes this easier and more instructive.  Collaborating with a lab partner can be a form of peer instruction, which has long been recognized as a useful tool for teaching physics in both labs and in lecture classes.2

If we are able to have students in the classroom in Fall 2020 they will likely be required to wear masks and to be spread out in the classroom to preserve “social distancing.”  The masks won’t be a problem, but being “spread out” is in direct conflict with working together as lab partners. One potential way to have students work together but preserve distancing would be to have one student working in the classroom and another connected via video chat. A problem with using a standard video chat application is that our laptop computers have a built-in camera that only faces the front of the computer, which does not easily give a view of the equipment. We could add an additional web camera, and then the person in the room could point it at the experiment.  Either way, using the computer for video would provide a static view (which admittedly is better than nothing) and would require the student in the classroom to continually adjust the camera.  A clear improvement would be if the remote student could control the camera themselves to look around as the experiment is being performed.   Unfortunately, cameras which can pan and tilt (and possibly zoom)3 which are compatible with common video conferencing systems like WebEx or Zoom are expensive,4 and we would need one for each lab station.

A note on terminology:  At SUNY New Paltz5  the word “hybrid” is applied to a course which has an in-classroom component and an on-line component.  But this is not very specific. The hybrid courses in our department implement the “flipped classroom” method, where students view content material such as recorded lectures online and then come to class for discussion and problem solving. Having some students in the classroom and others joining remotely via computer is another variation of “hybrid” but is different from a flipped classroom.  I will use the term “local+remote” to specifically mean a synchronous class or activity where some students are physically in the classroom and others join via computer, all at the same time.

Home Monitoring Camera

YI-Cloud Dome Camera 1080P
Figure 1.  YI-Cloud Dome Camera 1080P, a home camera which can pan and tilt.

A potential alternative to an expensive steerable web camera is a commercially available home monitoring camera (aka “nanny cam”).  The model I chose to test, shown in Figure 1, is the “YI-Cloud Dome Camera 1080P,” which sells for about $30 per unit.6 I chose this camera simply because I had previous experience with an earlier static camera from the same company. My family has used that camera to check up on my elderly mother when she was home alone (before the pandemic).  We called it the “Granny Cam.”  Other common uses are to watch pets at home or to keep an eye on a baby in another room. From my prior experience with the static camera it seemed that a similar  camera which is steerable would work well for connecting virtual lab partners.  And contrary to the implication in the name, use of  “the cloud” for storing video is not required.

Network Configuration

Setting up the camera is very easy in a home environment, but more complex on campus, where we use RADIUS authentication for the Wi-Fi network using individual usernames and passwords.  The camera is designed to use WEP or WPA2 authentication (using the SSID of the Wi-Fi network and the (single) password for that network), as is common for most home routers.  The camera has an RJ-45 jack so that it can be connected directly to wired Ethernet, but that only worked after the camera had been paired with my mobile phone app using Wi-Fi.   Since my phone connects to our campus Wi-Fi using RADIUS but the camera cannot, this presented some difficulty.

One way to get around this difficulty is to pair the camera and mobile phone while using a different WPA2 network, and once that is done then the camera can be connected to wired ethernet.  A remaining complication is that Wi-Fi won’t work if that WPA2 network is no longer available (e.g. if you paired the camera to a phone at home and then brought it into the lab).  It is likely we would want to use the wired Ethernet in any case to avoid network interference and congestion from using many of these devices in one room. (But I also found a way around this; contact me for details.)

QR code use for pairing a camera with the mobile app
Figure 2. QR code use for pairing a camera with the mobile app

The pairing process is fairly straightforward.   The camera starts in pairing mode when plugged in the first time, or after you press and hold a reset button on the back, and it gives voice prompts to indicate where it is in the process.   On iOS at least you have to allow the app to obtain your location — perhaps for added security?  The user enters the Wi-Fi network name (SSID) and password, which are encoded into a QR code (see Figure 2) which is displayed on the screen of the mobile device. That QR code is shown to the camera,7 which reads and decodes the QR code and uses the SSID and password to authenticate to the Wi-Fi hotspot.  After only a minute or two the camera is paired to the account used on the mobile app. It can then be accessed using the manufacturer’s mobile app from any device using that same account8, and the camera can also be “shared with family” to someone using a different account (an important feature discussed further below).

Although you cannot pair the camera on wired ethernet it is possible to switch between wired ethernet and Wi-Fi.  Whenever an ethernet cable is plugged in to the device it will switch to the wired connection, and when it is unplugged it will switch to Wi-Fi (if it is able to do so).   I have not measured the time it takes to make these transitions

These kinds of cameras are made to allow a homeowner to see the view from the camera when they are away from home.  In my lab I tested accessing the camera from off campus by turning the Wi-Fi off on my mobile phone and on an iPad and using my carrier’s mobile data network on both to verify that I could access the camera.  Even though I was in the same room, the packets had to get to and from the camera by entering and leaving the campus network, and that worked fine. I later verified that I could view and control the camera when I was 10 miles from campus.  There was a noticeable increase in latency when using the mobile network from a distance.

Gooseneck Mount

Placing the camera on the lab table did not give a good view of the equipment, which is also on the table, so it was necessary to lift the camera up to the eye height of a typical student.  A traditional camera tripod proved to be too tall when placed on the table with legs fully retracted.  The height would be easier to adjust with the tripod on the floor with legs extended, but the spread legs would then take up a lot of room that would otherwise be available to the student working at the table.

Lab desk showing the home security camera mounted on a gooseneck support which is clamped to the table.
Figure 3. Home monitoring camera mounted on a gooseneck support and aimed at a typical physics experiment (for a lab dealing with Ohm’s Law).
Home camera mounted on a gooseneck support.
Figure 4. Home camera mounted on a gooseneck support.

So to position the camera with the right height and direction I used instead an AboveTEK Heavy Duty Aluminum Gooseneck iPad Holder,9 which clamps to the table top, has a spring clamp which holds the camera securely by the base, and can be bent into position to match the eye height of a student but without getting too much in the way of the person working at the table (see Figures 3 and 4).  The camera base was tilted downward so that the remote student could tilt the view downward to look at the table.  Otherwise the downward tilt angle of the camera was too limited, while the upward tilt went all the way to the ceiling (which is not useful).

We might be able to construct our own gooseneck mounts using flexible metal wiring conduit mounted on the table with bench clamps (we have plenty of those) with a custom-made 3-D printed camera mount on the end.

Audio and Controls

A mobile app is available from the manufacturer for both iOS and Android, and testing shows that the interfaces are very similar, which means that documentation and training for students would not have to be different for the two platforms.

The camera has a two-way audio feature which lets the remote observer hear audio from a microphone built into the camera, and to say something through speakers also built into the camera.  There are two different modes for the remote observer to talk.  A button on the screen can be used for “push-to-talk” or “intercom mode,” meaning it has to be pressed and held while talking, which would not be the best configuration for lab partners.  But the settings can be changed to “hands-free mode” so that the button turns the remote observer’s microphone on continuously until pushed again to turn it off.  This would be the best way for lab partners to carry on a continuing discussion throughout the experiment.  The remote student would have to be given instructions on how to change this setting, since it is not the default.

showing the controls when the camera is first selected.
Figure 5. showing the controls when the camera is first selected.

The interface for controlling the camera is easy to use, with some minor complications.   The initial view is “portrait” with the steering  “joystick” control prominently displayed (see Figure 5).  But the view does not switch to a larger “landscape” view simply by turning the mobile device, as some might expect — one has to press the “spreading arrows” button in the lower right corner to shift to that larger view (see Figure 6).  One on-screen button allows the user to turn the audio monitoring on or off (either as a toggle, or push-to-talk mode).  Another lets the user take a still photo, which are saved to the camera roll on their own mobile device, and can also be saved to Google Drive or shared via email or text message.   Students could use this to take a photo of the entire apparatus, or parts of it, or perhaps of just a meter reading.  Another on-screen button lets the user record video from the session (again saved to their own mobile device).  An example of such a video is shown in Figure 7. A student could record the whole lab, or key parts of it, and review that video later.  In the expanded “landscape” view the camera steering controls are not obvious (but are also not in the way).  Tapping a small icon in the upper right of the screen (see Figure  6) expands the steering controls while hiding the other audio/video controls.  Tapping on the screen again will clear away all control icons. It’s all easy to use once you see it.

The steering controls are fairly responsive when one is on the same network as the camera.  A student using the camera from a dorm room or other location on campus should not have any troubles steering the camera.  There is a bit of a lag in the steering controls when accessing the camera from off campus. Tapping the controls and waiting to see the result leads to the desired results.   There may also be an audio lag, but that has not yet been tested.

Camera controls once changed to "expanded" view.
Figure 6. Camera controls,  once the view is changed to the expanded (landscape) orientation.

While the camera does not have a hardware zoom feature, one can zoom in software using the familiar “unpinch” gesture of spreading two fingers on the screen.  The camera has two resolution modes, “SD” and “HD”.  On a good network connection the HD video works well. I have not pressed the limits to see how a poor network connection degrades the video, or measured the bandwidth requirements.

Sharing the Camera

One key feature that will make it easier to use this device for connecting virtual lab partners is that a camera can be “shared with family.” This means that the camera can be paired initially with the account of the lab manager or faculty member who runs the lab and who always maintains control of the device. The video and audio from the camera can then be shared with a student who has a different account (created using their campus e-mail address), but the student cannot accidentally modify or delete the camera, and access to the camera can be revoked once the lab exercise has been completed (if that is deemed necessary).

I will also note that each camera can be given a name, and that name can be changed in the app settings.  We might, for example, change the name whenever a camera is moved to a different lab station.

Figure 7.  Example of data collection, as viewed from the camera. In this case, for an experiment to study friction. Note the manufacturer’s logo watermarked on the video in the lower left corner.


History Review Feature

The camera manufacturer has a subscription cloud service for saving recorded video, but this is both optional and unnecessary for our planned use of the camera. One can insert an SD card into the camera, in which case video and audio can be recorded automatically on the camera and played back by the remote observer.  This would, for example, allow the remote student to go back and review something that they missed or wanted to study in more detail.  The interface for this is straightforward: a time “scrubber” is shown at the bottom of the screen, and the user can drag the scrubber back to the desired time to view the recorded video (see Figure 6).  This history review feature is always available to the “owner” of the camera, but must be specifically enabled for the guest account to which the camera is shared — it’s off by default.

We will have to think about how we might use this history review feature, and whether it is worth the additional expense of an SD card for each camera. The camera works fine for real-time viewing without the SD card.  With the SD card it would be possible for a student with access to a particular camera to view not just their own work with their own lab partner, but the work of previous students who used the same camera.  That may or may not be desirable, or worth worrying about.  An instructor who was not present for the lab period could use this feature to verify attendance and participation, or to review student work to give assistance, or to evaluate problems with the equipment or lab documentation.

Desktop Client App

It would be useful for the remote student to be able to see the view from the camera on the larger screen of a desktop or laptop computer.  Until recently, this particular camera manufacturer only provided apps for mobile devices, and my own survey (possibly incomplete) of similar products suggests that this is a property of the commodity market.  It is a selling point for all that they work with manufacturer-specific mobile apps, many with Amazon Alexa, but there is little or no mention of access via web or desktop computer.

Fortunately, this camera manufacturer has recently released apps for both Mac and Windows. Unfortunately, the Mac app failed to run on MacOS 10.15.4 with a pop-up warning saying it “can’t be opened because Apple cannot check it for malicious software.”10   Further testing is warranted, but this is discouraging.   On Windows there is a similar warning when you go to install the software, but you still have the ability to do so. Once started, the app looks a lot like a mobile app, but still with standard Windows controls in the title bar.11

The app on Windows works to view from the camera and to listen to audio, and the controls work to steer the camera, but the intercom feature is missing, so the two lab partners would not be able to talk using the camera microphone and speakers. I also had a problem creating a new camera account on the Windows app, so a mobile device may be required for that.  The desktop app does show multiple cameras “owned” by the same account, so it would be handy for an instructor or lab manager to use to check on the status of all cameras while in use.  But the Windows app also seems to be missing the feature to share a camera with another account, which means that a mobile device would be required to share a camera with a student for the duration of an experiment.  In short, the Windows client app is behind the mobile app in several important ways.

Given all this, we should keep in mind that students might concurrently use video chat software such as Blackboard Collaborate Ultra (our primary video meeting tool for classes), or WebEx (also favored on our campus). In that case the students could talk directly to each other, face to face, and use the video meeting for audio as well.  Using both the steerable camera and the video chat could give the students an even better means of collaboration, and give the remote student an even greater sense of presence during the experiment.  The bandwidth required to support two video streams might be a limiting factor for some students. (TODO: verify that it’s not a limit on campus.)  On the other hand, the bandwidth required for even one video stream might be a problem for a student using a mobile data plan instead of Wi-Fi.

Multiple Remote Users?

Access to a camera can be shared with more than one guest observer, so it might be possible for a person physically in the lab to work with more than one remote lab partner.  Initial tests of several remote observers accessing the same camera showed some intermittent video buffering, but it was not clear that this was actually due to having more than one person viewing the camera — it might have simply been that the camera was too far from the router for a reliable connection.  A later test with the camera connected via wired Ethernet supported multiple users with no observed buffering. Further testing is warranted, but this is encouraging.

If more than one person can connect and use the camera at the same time, then this could also make it possible for an instructor to render assistance to students during the experiment without having to be physically present in the room, thus further supporting social distancing.

Signal Security

According to the manufacturer’s website12  the “requests” between the camera, mobile devices, and servers use secure HTTPS with a “two-way mutual authentication process to ensure that the user’s personal information is not compromised. Each device has its own key and certificate to authenticate with the server.”   The video from the camera to the user device is an encrypted Peer-to-Peer connection so that “only the end user can view the video content. Any possible interception happening during transmission information will only see scrambled and encrypted data.”

I also note that the  sharing system is designed to limit access to the camera to only the “owner” and to someone else the owner can designate via their campus e-mail address. We can also revoke the share after the lab exercise is over, if we need to do so. It is further possible to add a PIN code to the camera, so that the user has to enter that code to access the video stream even if it is shared with them.  Then access security is insured by both something they have (their phone with the app) and something they know (the PIN code).

Other Camera Features

Since this is a camera for home monitoring, it has other features that are probably not useful for the local+remote classroom use case, but some should be mentioned if only to warn the user to disable them lest they get in the way:

  • The camera has a motion detection feature where it automatically points to the source of motion. This does not work well in the lab during an experiment.  It is off by default (TODO: verify) and in any case should be disabled for lab work.
  • The history review feature can also be configured to only record when motion is detected. That might be useful for helping find a particular bit of video based on past activity, not just time, especially if there are long breaks between data-taking sessions.  (It is not necessary to worry about filling the SD card with video, as the device simply records over the oldest previous recordings.)
  • The status light on the front of the camera base can be configured to stay off when the camera is in use.  When it is on, the light flashes if there are network problems, and having the light on would be a reminder to the students that the camera is operating, so this feature should not be used.
  • The image can be rotated upside down, for mounting the camera on the ceiling.  Maybe there is a way to use this to give the remote student a better view?
  • There is a “crying baby” detection feature which one hopes is not necessary (but putting our students through all these complications just to get their degree might trigger some justified crying).
  • The camera has infrared LED lighting which can be used to view and record in otherwise total darkness.  We probably don’t need this feature.
  • The camera microphone can be disabled in the settings.  But since it can also be turned on or off by the primary user controls, totally disabling it would only be useful if we always use video chat in addition to the steerable camera, and it would be confusing if students decided later to use the camera audio.

Other Manufacturers?

I only tested this single camera from one camera manufacturer. I might test others, and I might even post a comparison.  Or maybe not, if we decide that this camera satisfies all our requirements. Because these are commodity devices for home use I expect that similar cameras on the market from other manufacturers will have similar features.   I would welcome reports from readers about which needed features are present or absent in some other make of home camera.

If using these cameras to enable virtual lab partner collaboration works as expected, the market for such devices might get tighter, just as it is tight now for webcams.  In that case using cameras from other manufacturers, and maybe even mixing them, might become a necessity.

Legal Concerns

Even though it appears that there are no major technical problems with using this kind of camera as proposed, there may well be legal or policy hurdles to be surmounted.  At SUNY New Paltz I’m told that installing devices that capture video or audio from a classroom space requires approval from the University Police Department (UPD), and possibly the HR department as well.  I am hopeful that we can get such approval, because we already have lecture capture cameras installed in our labs, and those must have already been approved.

Concern has also been raised that we must insure that we comply with NY State Penal Code Article 250.00, which deals with wiretapping and interception of electronic communications.  One type of crime described there involves a third party who intercepts signals meant for someone else.  If the peer-to-peer video stream between camera and observer is properly encrypted, as the manufacturer claims, then wiretapping and interception by a third party should not be possible, though our IT staff may need to verify those claims of encryption and that it is adequate. Another type of crime applies to someone who sets up “an imaging device to surreptitiously view, broadcast or record a person” in various private situations (NYS Penal Code Section 250.45).  Clearly, lab cameras used as described above are not “surreptitious.”  Furthermore, according to NYS Penal Code Section 250.65  the provisions of §250.45 do not apply to “video surveillance devices installed in such a manner that their presence is clearly and immediately obvious.”   As long as the cameras are as visible to students as they are in the photos above, with the blue light on to show that they are operating, then there should be no problem.  However, it is clear that the University Police and  lawyers will have to render judgement on all this at some point.

The purpose of this article has been to see if there are any technical hurdles that prevent the use of commodity “nanny cameras” from being used to enable virtual lab partner collaboration, before we get as far as involving administrators and lawyers.   So far, so good.

Notes and References

  1. Troubleshooting equipment is an excellent model of the scientific process of forming a hypothesis and then testing it.
  2. See, for example, Peer Instruction, A User’s Manual, by Eric Mazur (Prentice Hall, 1997)
  3. Cameras that can Pan and Tilt and Zoom are called “PTZ” cameras.
  4. A Logitech PTZ Pro 2 Camera costs over $750 on Amazon, or  $850 direct from the manufacturer.
  5. It may be that “hybrid” has the same meaning throughout SUNY, but I have yet to confirm this
  6. The current price for the YI-Cloud Dome Camera 1080P from the manufacturer is $33.99, with free shipping only on orders over $35. The current price on Amazon is $29.99 with free shipping.
  7. I tried saving a screen shot to use later to add another camera, but I later found this doesn’t work.   The information in the QR code is not encoded as plain text, and so likely includes a time or location to prevent just such a “replay attack”.
  8. Beware, it seems that an account on the mobile device and an account on the manufacturer’s web site are not the same thing.
  9. AboveTEK Heavy Duty Aluminum Gooseneck iPad Holder, about $30 from Amazon at the time of purchase, but the price keeps going up.  I also found these useful for making home-made document cameras. I suspect the price has gone up because others have discovered that too.
  10. On an older Mac I was told it require MacOS 10.11 or later. Alas, that machine was too old to run the app.
  11. Watching the libraries that were installed with the Windows app showed standard graphics libraries and the Qt interface library.
  12. How do I ensure the security and privacy of my videos?”  YI Technology Help Center,

Using a Document Camera for ‘local+remote’ Instruction

Using a Document Camera for ‘local+remote’ Instruction

This article provides configuration information for using an in-classroom document camera so that the content it displays is available to both students in the classroom and those joining via video meeting software (such as Blackboard Collaborate Ultra).  These instructions are particular to our Physics Labs, but the general idea should apply more widely. (1050 words)

Introduction and Motivation

The COVID-19 pandemic caused all instruction at SUNY New Paltz to move online in March 2020, after an extended Spring Break.  If we are able to have students in the classroom in Fall 2020 they will likely be required to wear masks and to be spread out in the classroom to preserve “social distancing.” Spreading everyone out in a classroom may pose problems —  in some cases it just won’t be possible to have all enrolled students in the same room if they have to all be at least 2 meters away from each other.

One way to deal with this is what I will call  “local+remote,” which means a synchronous class or activity where some students are physically in the classroom and others join via computer, all at the same time. Students observing or participating remotely might watch via a classroom lecture capture camera (we have these in our physics labs) or a webcam, or maybe even a “nanny cam”.  The particular mode I consider here is that the instructor presents their content using a document camera, and that content is both displayed on the projection screen in the classroom and is shared with remote participants using video meeting software (such as Blackboard Collaborate Ultra).

The instructions presented here apply to the AVer F50-8M document cameras found in the Physics Labs in Science Hall at SUNY New Paltz, used with Blackboard Collaborate Ultra.  This model of document camera is also used in other classrooms in Science Hall, but classrooms in other buildings may be different.  Even so, the general idea may still work with other document cameras.  If you are unsure, ask Instructional Technology Services for assistance, and try everything well before your class starts.

Cable Required

To make this work in our labs required an additional cable connecting the AVer document camera to the computer.  This cable connects to the document camera with USB-mini B, and connects to the computer via standard USB-A (what most people think of as “regular USB”).  Actually, in our labs the cable from this additional cable from the document camera connects to a USB-A extension cable, which then connects to the computer. In SH 157 and SH 159 the extension cable is already routed through the internals of the instructor station from the back of the computer and up through a hole in the desk.   In SH 160 the extension cable is currently external

To use this kind of document camera in any other classroom you will need both these extra cables.  Why?  The video from the document camera normally comes out of the HDMI port to the Crestron system to be routed directly to the projector, bypassing the computer.  The USB-mini B cable takes video output from the document camera to the computer, but the distance from the document camera to the front of the computer is far enough that you likely also need an extension cable (we did).

Also note, not all classrooms on campus have the same make and model of document camera, so you should confirm which kind of cable is actually needed before assuming another classroom is just like our physics labs.   Test everything before you teach your class, and ask Instructional Technology Services for assistance.

Classroom Setup

  1. To begin, turn on the document camera (press the power button).   It takes a while for it to wake up and be recognized by the computer, so do this first.  Verify that the USB cable is plugged in to the back, and (if you can tell) connects the document camera to the computer.

    Figure 1. Crestron Control Panel.
    Figure 1. Crestron A/V control panel with the Display “ON” and “PC” selected as the video source.
  2. Next, wake up the A/V control panel by touching the screen, and then turn on the projection system by pressing the “DISPLAY ON” button (see Fig. 1).  This should cause the projection screen to drop from the ceiling.  Select “PC” as the source for the classroom projection system.
  3.  Plug it your external webcam (if you have one1) and  position it so that your students will be able to see you while you are teaching.
  4. Turn on the computer and log in, then start a browser (Chrome is recommended over Firefox2– at least for now).

    Blackboard icon for opening the controls for a Collaborate Ultra meeting
    Figure 2. Controls icon
  5. Then start the video meeting, using Blackboard Collaborate Ultra.  When you are starting the meeting you will configure your audio and video.  Pay attention here to your choices, because you will be able to select either the webcam or the document camera as the video source, and when you start the meeting you will want the wecam (if there is one).   You might prefer the document camera as the audio source, since you’ll be speaking nearer to it than the webcam once you are presenting from it.

    Blackboard Collaborate Ultra sharing control icon
    Figure 3. Sharing icon
  6. In the video meeting, open the control panel on the right (using the purple left-chevron icon shown in Fig. 2) and select the “sharing” menu (the icon shown in Fig. 3). From the sharing menu select Share Camera. You will then be given the choice to select either the webcam or the document camera.  The
  7. Teach your class using just the document camera to present equations and drawings and other visual content, and both local and remote students can see it, and hear you, and see you.


Document camera image projected in a classroom and shared in a video meeting at the same time.
Figure 4. Document camera image projected in a classroom and shared in a video meeting at the same time.

Audio Headset

To be able to hear students who are remote you will likely need a headset, but to be able to hear students in the room you will want to keep one ear uncovered.  One way to accomplish this is to use ear buds with only one of them in your ear (the one with the microphone).   This has the advantage of getting the microphone closer to your mouth.

Perhaps even better is to get a “Truckers” bluetooth headset, which can connect to the computer wirelessly, has a boom mike, and a speaker for only one ear (since truckers need to keep one ear uncovered for safety).   Most let you use either ear.

Either way, you will have to configure the computer to use ear buds or the bluetooth headset for audio input and output  (documentation forthcoming).  Be sure to test this before you teach your first class.

Notes and References

  1. It is possible to teach using just the document camera but not a webcam, but then your students won’t be able to see you, only the image from the webcam.  If you don’t have an external webcam, the AVer F50-8M has a built-in microphone, so you will not need an extra microphone
  2. Firefox has problems sharing an application window (not the whole screen) in Blackboard Collaborate Ultra. NEED TO TEST THIS WITHOUT USING SPHERE2!  Sharing a single application window with Chrome had no problems. Microsoft Edge has not yet been tested.
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