Hi all, I have created, am the owner of, and have been planning a major project with my university for automatic lecture recording. I'm surprised that U of T, the largest Canadian university is so behind in terms of mass practical applications of technology. The entire project will be completely open source, non profit, and university (student) run. I'm seeking advice from you guys with respect to the hardware implementation of the system. Currently, lecturers use a radio microphone link that transmits audio from a small microphone and transmitter attached to their body to the podium, where the audio is received (I assume via a standard 3.5mm jack) and sent to the speaker system for amplification. My design aims to be as non-intrusive, simple, reliable, and compatible, and cost-effective as possible. I proposed (but can be changed) a small device (computer) which taps into that analog audio signal at the podium (like a T splitter) and records that audio, which is then later made available to students for download. 1. The first major component of the field hardware is the computer module. Timing of the availability of the Raspberry Pi is perfect for this application. If I can manage to order about ~200-300 Raspberry Pi units initially, I can start the implementation right away. If not, I have been considering small, rugged plug computer that I've been keeping an eye on for the past year or so. Comments/suggestions on this would be appreciated. The computer module should have ideally: analog audio ports for signal input (like mic and line in jacks), USB ports, provisions for ethernet/wifi, provisions for attaching a small touch display, enough processing power for real time audio recording, AND video recording in the future. So far, the Raspberry Pi seems to be perfect for this application, but I don't know if can get 200+ units by next semester (January). At the very least, I should get a (incomplete, not fully cased) proof of concept up and running in at least 10 rooms before the start of next semester. 2. The second major component of the filed hardware is the analog electronics used for tapping into/splitting the audio signal from the receiver (which normally goes to the speaker system for amplification). I need to make or find an off-the-shelf unit for this purpose. Requirements: - It doesn't *have* to be in a single unit. The functionality can be spread out to two units, for example, if you guys suggest that it would be a better way to go. - Active splitter with manual +/- gain adjustment, for example: a small knob that can be turned if needed to increase/decrease volume. - One or more inputs and two or more outputs. One output will be connected to the lecture room's speaker system, and the other output will be connected to the computer module for processing and recording. - Should have parallel sockets on all inputs and outputs for various types of audio jacks so it's compatible with whatever common audio equipment the professor/university uses. I need to go and survey the different types of jacks being used at the moment. - Should to be able to control the splitter module from the computer module. The computer module needs to be able to turn the splitter on/off. Not sure if this is an important requirement though. - Should be reasonably priced. - Not all lecture rooms/professors are equipped with microphones, especially in the smaller rooms, so I will need to set up independent microphones in those rooms. It might be a good idea to specify that the unit include the appropriate mic inputs and biasing for external microphones, as well as "phantom power" used in studio recording microphones, if such a mic is used. This functionality can be in a separate unit - probably a good idea to have it separate from the splitter unit anyway. I'm really quite unsure about the best way to go here, with respect to the splitter unit. Is anyone aware of a unit that can do the above? Or would I need to design my own? (I don't mind). 3. The interface that the lecturer uses at the podium should be super easy to use and simple in design. Should also be rugged, to withstand angry professors mashing away at it. I'm thinking of using a normal (non-touch) LCD screen behind glass, with a USB (numeric) keypad used to control the device. This can always be changed as necessary. 4. The device should be well electrically shielded from audio interference and shielded from physical damage. The casing should hold the computer module, power supply, and splitter module. - Solid (metal?) case, with mounting holes to bolt it to the podium if necessary. - Obviously, must expose the appropriate ports. The USB WiFi module will probably need to be as exposed as possible. - Needs to have a glass/plastic transparent panel over the small LCD screen to prevent damage to the display. It will most likely need to be custom designed, but I don't plan to do it myself as I don't know anything about 3D design. No idea where to start. Any suggestions? The whole unit will be braindead-simple to install for the engineering kids I'm going to assign the installation task to. Carry unit to podium, plug into power outlet, connect speaker system to the unit, power on, and proceed to the next room. The professors then simply plug in their mic output into the unit and everything else is taken care of by the unit. Simple as that. The unit will be on continuously, and be recording for 12 hours a day. At night, it will perform the required automatic audio post-procesing before uploading the finalized audio file to the file server. This is why the reliability of the analog components is essential. The analog part needs to be working at all times. Eventually, hot standby functionality will be added to the system to switch over to a secondary unit in case of failure. These are just preliminary specs for the hardware unit. Obviously, I need to spend a lot of time thinking this part through as I want to build this unit to last many years. I'm unsure about a lot of it, which is why any tips/suggestions/comments about anything at all from you guys is highly appreciated. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .