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RCHourglass DIY Lap Timing (AKA Cano revised)

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RCHourglass DIY Lap Timing (AKA Cano revised)

Old 12-14-2018, 02:13 AM
  #361  
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Originally Posted by contacto75
Is it possible to test the decoder without the amplifier?
I'm afraid no. You might want to try the simplified payalneg amplifier. I haven't build one myself so I cannot help you about that or say which one works better...

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Old 12-15-2018, 08:59 AM
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Originally Posted by mv4wd
I'm afraid no. You might want to try the simplified payalneg amplifier. I haven't build one myself so I cannot help you about that or say which one works better...
May be yes, if you connect only one wire with a capacitor from the antenna of the transponder to the decoder

Thor
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Old 12-18-2018, 01:05 PM
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Finally I got the thing working on the nitro offroad track, by adding external 5V supply for decoder.
But as now the winter session starts I have a lot of missing detections with electro 1:10 class on carpet.
Detection is working fine at no throttle or at full throttle.
But in case of part throttle I have no detections.
In the picture you see reading at loop amplifier output at part throttle.
The spikes are coming from the motor (8kHz), at the left side you can see a transponder message.
So for me it is plausible that I canīt get detections as every message is disturbed by motor noise.
I am just wondering how AMB handle this situation?
Perhaps somebody knows how to improve this?

dropbox .c o m
/s/x51y6byj0iwdrbt/IMG_20181218_180501_klein.jpg?dl=0
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Old 12-18-2018, 04:13 PM
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That noise seems really high and also the timing seems strange.... it seems like bursts of high frequency noise (similar to the tx frequency)... why should that change to a better situation on full throttle... maybe less pwm from the esc? Anyway the level of that noise seems a lot higher than the transmitter itself... I'm guessing how do those esc really pass emc test... Are you sure the noise is not injected in the transponder antenna? Are you using amb transponders or rchourglass? Maybe have a try with a separate battery and not the bec. I run 1/10 electric buggy and my friends have tested with 1/8 electric buggies, still the performance where not really affected by speed. Of course faster speed means less hits. Our finish line is in the middle of a straight so probably 90% of the times full throttle but under acceleration. Working with real frequency demodulation would improve noise rejection....
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Old 12-20-2018, 04:28 AM
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It seems that emc was not the high priority for the esc guys. I can measure high ringing at the esc terminals at every change of pwm (falling and rising). At full throttle pwm is 100%, so ringing is only at motor commutations. I tested without mounted Amb transponder and the noise is still the same at loop amplifier. Unfortunatelly all of the tested esc shows the noise, overall I checked 7 different escs.
The frequency of the noise is below 1Mhz, do you think it would be possible to add some filter?
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Old 01-27-2019, 02:03 AM
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Default Amb20 Decoder diy transpinders

Hi guys
Does anyone inow what diy PT will work with the Amb20 decoder ?
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Old 01-28-2019, 04:25 AM
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I don't have access to Amb20 transponders, sorry. If the signal is still 5MHz BPSK with the same preamble, monitor mode could be uset to capture the transponder packets a see if the firmware can be modified to mimic them.
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Old 01-29-2019, 09:27 AM
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Sorry for the late response, to many work....

On the Amb20, the frequency is about 3.68 MHz and i don't have the time to work on.
I have the idea to try to mix the frequency to have 5MHz and try to read with the decoder

Thor
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Old 01-30-2019, 12:00 AM
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Thank you for the response guys. Much appreciated.
We basictly sitting with an AMB20 system at our track but the hand out transponders is starting to pack up.

Any suggestions on what PT will work on the AMB20 or what modification i can make on the decoder to be able to register PT ?
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Old 01-30-2019, 02:48 AM
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The RCHourglass transponder can be easily converted to send a 3.68MHz signal (or 3.58MHz...these are 'standard' values). The crystal must be changed from 5MHz. The antenna must be retuned for the new frequency (different number of turns and/or capacitors).
The problem is finding the packet data that must be sent, and changing the transponder firmware data. Also (small change) fine tune the delay time between packets since it's related to the system clock.
How to find the packet(s) sent? Use an oscilloscope and/or run a modified version or the RCHourglass decoder that runs the front end at 3.68MHz. The decoder probably needs a 'relaxed' preamble detector and 'Monitor mode' must be used. It's also possible that the transmitted telegram is shorter than RC3 transponders, so the trailing part of the packet seen in monitor mode is probably garbage.
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Old 01-30-2019, 03:59 AM
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To my knowledge the AMB20 does not work with packages but with tone coders/encoders.

I know someone who made a simulair systen based on the idea of the AMB20. He made transponders with an 5MHz AM transmitter and a tone coder. On the other side he made an AM receiver with tone encoders which were read on the parallel port of the PC.

Every transponder had theit own tone frequency.
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Old 01-30-2019, 08:27 AM
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Originally Posted by Roelof
Every transponder had theit own tone frequency.
If that's the case, I'm afraid there's no way to easily modify RCHourglass transponders to simulate AMB20 transponers...

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Old 02-03-2019, 01:31 PM
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Hi guys,

great thread going on here. I’m a member of my local roc boat club, where we race various classes of boats, we currently do manual lap counting but are looking to bring in some sort of electronic counting. I’ve been following this thread for a while now, but need a few questions answering.

Does anyone one know if this setup will work on water with the loop antenna suspended 30-40cm above the water?

second question is are there any component lists for the transponders/decoder & amp?

thanks

blazin
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Old 02-04-2019, 09:27 AM
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At least another user is using a desgin derived from Cano decoder (from which RCHouglass comes from) for rc boat timing. What he told me is that he's using a passive loop (100% Mylaps compatible) had to redo the loop amplifier and 'clean' the power supply to lower the noise and be able to use a longer loop needed for boat racing (2x18m). Sorry but I don't have any more details about it.
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Old 02-11-2019, 01:45 PM
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Hi! I'm ready to start the decoder build but i found loop amplifier schematics difficult to understand. Those jumpers blow my mind. What are they for? I only know the basics on electronics. Thank you in advance
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