track telemetry - data radio

[AndreyB]

Well, this is scary Chinese

What about this telescoping - would it help simply because it's longer? Anything from Radioshack stock to help me?

[kb1gtt]

telescoping is bad for your application. Get a fixed geometry one specifically for 900MHz and preferably with a fat diameter element(s).

[AndreyB]

What about https://www.amazon.com/gp/product/B00KY4Q7DG? IIn comments they say that it is https://store.weboost.com/products/311125

[kb1gtt]

For $20, I think you can get a better antenna.

For $9 you can get this 3 pack which claims 5dbi and includes gold plated connectors.
http://www.ebay.com/itm/3-Pack-10-ft-900-MHz-5-dBi-Mag-Antenna-with-Magnetic-Base-SMA-Male-Connector-/351831450090?hash=item51eac9e1ea:g:StUAAOSwOgdYvvUV

I do not like it's claim of 2SWR that's not good.

Does this adapter look like it would fit on your transmitter device? I'm farily sure it would accept the above antenna, and would allow you to connect that antenna to your radio device.
http://www.ebay.com/itm/SMA-Female-To-RP-SMA-Male-connect-SMA-to-RP-SMA-RF-Connector-Adapter-USA-/111516107525?hash=item19f6e0c305:g:-UkAAMXQVERSrf1P

With longer waiting times, you can get this mag mount with 7 dbi of gain.
http://www.ebay.com/itm/Magnetic-Base-SMA-Male-GSM-GPRS-Magnetic-Antenna-7dBi-900-1800MHz-with-3m-Cable-/282241130426?hash=item41b6e1dfba:g:K2EAAOSwx2dYGWVo

Key things to look for in this kind of antenna include gold plated connector, higher dbi is better, with about 10ft or less of coax cable.

For the base station, you could get this tripod.
http://www.ebay.com/itm/2-FT-Antenna-Tripod-Mount-Mast-Support-Roof-Top-Off-Air-Takes-Up-to-1-25-OD-/391463841124?hash=item5b25102d64:g:-bIAAOSwubRXL-lA

You would want a pole for that. You could use plastic electrical conduit, they make these with expanded ends, but that's also typically a 10ft length.
https://www.mcmaster.com/#7912k5/=17jrc9w

You can probably find equivalent at your local home train wrench store, or Lowes. You an also get a length of pipe, then glue on these adapters, such that you could have 2ft lengths which are easier to assemble and easier to pack in the car.

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I can't seem to find many pole mounted 900MHz antennas. Perhaps the best way is to get a plate on top of a pole, then put on a mag mount.

You can also get these portable flag poles. You park your car on it to hold it down, and it comes with sections of pipe which can be assembled.
http://www.ebay.com/itm/Portable-Flagpole-Tire-Mount-Aluminum-Lightweight-Tailgate-Flag-Pole-Stand-Kit/122011299991?_trksid=p2047675.c100009.m1982&_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D40130%26meid%3Df43adc5712064dde8d2a59270ebf9da9%26pid%3D100009%26rk%3D1%26rkt%3D2%26sd%3D380818607825

[AndreyB]

Thank you for the great links! Slow orders were placed.

[stefanst]

I believe @ first suggested this: Use a small computer, like raspberry pi to handle rs232 <-> TTL serial , buffer the data and transmit as needed from the car.

Raspberry Pi zero is tiny, needs only 5V/1A and has native USB (which can be your RS232 with just a $10 converter) and native TTL serial. All you'd need to do is hook up a power supply, write a quick little buffering script and off you go!

Here's the Pi zero compared to our brainboard.

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[puff]

seems you are entering the linux zone?

[stefanst]

Been in the linux-zone -in a very amateur-ish way- since 1994 when I installed my first linux server
Interestingly there is a Chibios port for Raspberry Pi, so we *may* be able to get @ to hop on board. But I have no idea how actively this port is being developed.

[puff]

from my understanding, besides chibi os port, it also need a port of that radio control software to chibi os?

[stefanst]

Short answer: I don't think so.

Long(er) answer:
You need the control software to set up the radio, but for operation it is not needed.The radio accepts serial data in clear-text. I'm sure we could sniff the port and figure out the commands for setting up the radio as well, but there's really no point in doing that. The control software works reasonably well as is.

[puff]

i didn't get it - so the purpose of that RPi is just to filter out the unnecessary data and then transmit only the needed data?

[stefanst]

The Rpi would serve dual purposes:
1. Convert from RS232 (which is what the radio uses) to TTL serial (which is what the rusefi board uses) by means of connecting a converter that @ already has connected to the RPis USB port. This could certainly also be accomplished by means of a TTL-RS232 converter.
2. More importantly: Buffer the data. Maybe even compress it. The radio only has a 256 byte buffer. We anticipate communication breaking down on the track for periods of time that require a larger buffer, so we need to insert something to take care of that.

Granted the RPi is immensely overpowered for the task at hand. But considering that it comes at a $10 pricetag and I already have one in my parts bin which isn't used, I say "So what?"

And of course there's other neat things you can do with it now that it's getting data from rusefi- like a display connected to the native HDMI port.

[puff]

HDMI port, yummy!

[AndreyB]

At 60% anyone would treat himself to a 20ft mast and a 3" tripod!

But these new toys stay at home and it's track weekend for me!

[AndreyB]

So http://www.ebay.com/itm/33ft-10M-Antenna-Extension-Cable-Cord-RG174-RP-SMA-Male-to-Female-Adapter-Router-/272654001151 or http://www.ebay.com/itm/49Ft-WIFI-Antenna-Extension-Cable-SMA-Male-to-SMA-Female-Switch-Pigtail-RG58-15M-/191876941643 or do I _REALLY_ need to extend data cables and not antenna cables?

[kb1gtt]

I suggest aiming for a shorter coax. The coax is lossy, which means the energy that can get out of the antenna is less as it gets absorbed by the coax. As well the energy you hear is less. Per the below you can do some basic calculations to get a feel for your losses.
http://www.qsl.net/co8tw/Coax_Calculator.htm

Notice power out is 44% for this from 10ft length

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It drops to 8% at 33ft.

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It drops to 2.4% at 50ft.

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The receiving side is done in db which is not as intuitive as the output watts. For gut feel sake, keep in mind that you have the same losses on the RX side as you have on the TX side. The longer the cable you use, the more you are whispering, and the better your hearing protection is.

[AndreyB]

Gotcha, so 30 ft RS232 data cable, not antenna.

[kb1gtt]

Yes RS232 cable is much better.

[AndreyB]

Cool website - http://www.theantennafarm.com/catalog/antennas-191/mobile-antennas-192/900-mhz-range-199/

[kb1gtt]

I see glass mounted antenna's, and want to suggest caution about glass mounted stuff. That is very lossy. It's a nice no hole in the metal or scratched paint solution, but the antenna performance if very bad.

I also see they have NMO which is good, but requires you to punch a hole in your metal roof.
http://www.theantennafarm.com/catalog/larsen-nmo900-951.html

[stefanst]

Considering that the car has no glass, other than the windshield, and the roof already has a bunch of holes, it seems punching through the roof will be the way to go

[AndreyB]

Weird. Now I can 'Read Radio' with just three wires - GND, RX & TX. Handshaking NONE, no DCD wire needed any more.

[AndreyB]

Short version: PROGRESS!

Longer version:
Radio is real RS232 (negative 6volts levels)
rusEfi/Frankenso has TTL (positive 5 levels), so a TTL<>RS2332 voltage level translation is needed

As a step towards rusEfi talking to radio, I needed my laptop to talk to the radio via USB<>TTL device connected to TTL<>RS232 device. Things were not working. The only successful communication between laptop and radio was from a monolith USB<>RS232 device which would not be an option for rusEfi stm32 firmware/ardware.

Jared has suggested a loopback between while known good USB<>RS232 device, and Frankenso board (without brain board) acting as FDTI USB<>TTL connected to one of the TTL<>RS232 modules. That was a brilliant idea! Second TTL<>RS232 I've tried has worked - I've got putty on COM8 talking to while USB<>RS232 connected to blue RS232<>TTL connected to FDTI Frankenso connected to laptop on COM11, and I've got both putty instances talking to each other! This has proven that both Frankenso and blue RS232<>TTL are operation as expected.

Radio (male rs232) was still not responding to this blue RS232<>TTL. Tried flipping TTL jumper wires - no success. Jared's second idea was to make a flipped DB9 male/female cable - and this WORKED!

Now I have laptop connected to Frankenso without brain board, with PC10 pin/orange jumper wire on Frankenso wired to RXD pin on blue TTL<>RS232, PC11 pin/yellow jumper wire on Frankenso wired to TXD pin on blue TTL<>RS232, with a three-wire DB9 cable with RX and TX pins cross-wired, talking to Laird Connex CL4490 radio!

Next step "should be easy" - having rusEfi firmware transmit gauges data over radio link.

[AndreyB]

Got telemetry working across my living room!

baud rate 9600, limited blockingFactor from 400 to 100 in order to get below radio buffer size. TODO https://github.com/rusefi/rusefi/issues/429

[kb1gtt]

Sweet, If you need any more help learning how to talk to yourself, I'm apparently the guy who knows how to do that successfully

[kb1gtt]

Now that you have it working, I would suggest trying it with out the 232 module. You have about a 30% to 40% chance that it will consider 0V, -6V and -12V all to be a "1", and 5V, 6V and 12V all to be a "0". Now that you have validated you have the proper baud, parity, packets, etc, I would suggest trying it with out the 232 translation device.

Also now that you have it working, I suggest you take a picture of it, such that you can remember what wires were connected to what when it was working.

[kb1gtt]

Oh, also keep in mind that your 232 device might be inverting the signal. AKA -12V is a 1 in 232 land, but that is likely 5V in TTL land. When you try TTL you may need to flip this such that 0V is a 1, and 5V is a 0.

[stefanst]

To deal with the line-of-sight restriction, you could fly a drone as a relay. Should probably be gasoline powered though to get a decent amount of run-time....

[kb1gtt]

I've used a helium filled weather balloon before. Perhaps you could get an orange one, then put EFI in the middle with white paint.

[AndreyB]

So I was told to extend RS232 cable, not antenna cable. Data modem goes on top of a pole inside a 2l water battle for water-proofness.

RS232 let's start with three wires - GND/RX/TX, and I would also need 8 volts DC power supply - that's two more wires.

1) should I combine power supply GND and RS232 GND wires into one conductor? This case I can run a 4-conductor wire I've got instead of 5-conductor where I would have to use two wires.
2) how would say 40ft of 20 awg wire work for RS232? 40ft 22awg wire? That's a 20ft pole and 20ft just in case.