hi guys,
can we use cano loop amp with amb rc4 decoder?
i don't want to buy the most expensive cable in all world :)

No. The loop amp is powered from the main decoder board though the coaxial cable. I'm guessing the AMB cable is unpowered.

You can make your own loop. Just need to add a resistor to the middle (forgot the resistor number).

It works without resistor as well. I've used this stuff for testing above ground.

the official massively overpriced cable refers to a 470 ohm resistor.

why? someone smarter me will hopefully reply.

Hello boys,

I have problem:

1. Putty or other terminal from comport can read clear data only on the 38400 baudrate speed. This is OK? Because Howard in post #251 write:

"PC INTERFACE:

Logic-level RS232, 115200 baud, 8 bits, 1 stop bit, no parity, no handshaking, no flow control."

2. When running Zlaps, and connecting decoder I have alarms: Com port Error: com1

3. This is normal received line from putty:



250000000F6C61
25000000101129
70000000149AB6
7000000014E0F1
7000000015A8D5
70000000161E59
70000000179F47
7000000017D6AA
70000000011710
7000000001BD2F
700000000293F1
7000000002C1DC
7000000002DA2C
7000000002FFFF
?

All logs are from AMB transponder 3444425

Thanks for answers!

Andrius.

There's definitely a problem. Does your com port support 115200 baud? Do you correctly receive the power-up message?

Yes, pc support 115200 baudrate, but at this speed I receive only sequence of symbols. Your startup message I can read and digits I receive only at 38400 baudrate.

Then it sounds like you have an incorrect crystal frequency or a bad divider (U61). The microprocessor must run from a 20 MHz clock.

Have you used a third-overtone crystal? The oscillator requires fundamental-mode. Since your baud rate is 1/3 of the design value, I think this is a likely culprit.

We now have over 100K views of the thread! :)

Awesome post howardcano !!

Can someone send me a quote for a finish (solder, enclousure) cano decoder ready to plug and work??

Thanks!

Hi Howard, after my version of your transponder, I'm considering making a decoder. In the thread other options have been named (arduino, fpga etc).
Do you think it's possible to decode using 'off the shelf' electronics to make the project even easier to replicate? One interesting idea was the use of a radio usb dongle. From my investigations it seems that 5MHz needs a HW modification or an upscaler to be read. Also the data received must be BPSK decoded and 'injected' in the timing software, and this can be tricky, and I don't know if freq lock is fast enough. Another option is the Papilio FPGA board that is usb connected. Making an FPGA version of your circuit would still need external R/C components for debouncing/histeresis on the preamble decoder, right? The plus would be the easier way to emulate the serial comunication and a reference open source hardware that can be bought. The only custom circuit would be the 'wing' (shield in arduino world) for the analog input/amp. Do you have any suggestion?

I don't know of any off-the-shelf devices that could demodulate the 5MHz BPSK signal, but I also would not be surprised if one existed. So far no one has mentioned in the thread that they have found one.

I think the FPGA is a great way to go. The difficult part-- the demodulator-- requires no analog components, and it should be easy to also include in the FPGA other circuits (for instance, to detect and strip the "preamble") if one desired to reduce the workload on the microprocessor. The only analog circuits necessary are the loop amp and phase detector amp, and these are very simple.

Please keep us informed of your experiments!

My mistake, I was looking at the first revision, not the digital one. Right now I'm investigating how much 'horsepower' I need and find a suitable low cost device. I'm new to FPGA, but willing to learn... The main design decision I'm focusing on is between a loop>serial interface (like your design) or something more self contained that can work in standalone mode (maybe with a wifi connection and an android app) to give personal results to multiple drivers (or do both...).

Have I sent you the zip files with the project documents?

If you (or any other reader) would like to receive them, send me a private message with your email address.

Hello everyone,

I've just discovered this thread while I was researching for lap counting systems and vehicle detectors. I would like to use a system of this kind for fpv multicopter racing, and i was wondering if the decoder loop can be mounted as a gate and if it will detect the transponders as the multicopters pass through it.

You have made a great job in this thread, and also in the transponder thread, as it helps a lot to understand how actually the system works, mostly for me the analog and RF parts of the designs.

I've seen some fpv races using the infrared based i-Lap system, but I would like to evaluate other alternatives.

Thanks for all this documented work!