|
Having been peripherally involved with a couple small-scale commercial electronics projects, I know FCC and CE testing is expensive and time consuming. I often wonder how much of the RC stuff that comes out of China REALLY gets certified, and how much just gets a sticker that says it has been. I just don't see how turnigy/hobbyking/orange/etc can afford to go through official testing for all their products with their razor thin margins.
In any case, I'd be willing to take my chances. |
I agree, the majority of the China stuff that is not produced for the name brand NA market, probably is just a stamp, and no real approval has been obtained.
Now, food for though.....if a decoder/system was offered for sale in a kit form (unassembled), would the seller require the FCC/CE testing approval to be legally sell the kit? I have no idea, but I'm sure someone has looked into this. I would think that there would be many clubs willing to assembly a kit, to have a working system for the fraction of the cost of the competition. |
Originally Posted by brew99
(Post 12614415)
I agree, the majority of the China stuff that is not produced for the name brand NA market, probably is just a stamp, and no real approval has been obtained.
Now, food for though.....if a decoder/system was offered for sale in a kit form (unassembled), would the seller require the FCC/CE testing approval to be legally sell the kit? I have no idea, but I'm sure someone has looked into this. I would think that there would be many clubs willing to assembly a kit, to have a working system for the fraction of the cost of the competition. It's not okay to purchase a kit, assemble it, and then sell it to someone else, or to simply charge for the assembly labor. |
I wonder if a "90% kit" could be constructed to skirt the rules. Have most of the components (all of the SMT parts, obviously) pre-soldered and the chips pre-programmed, but leave a couple key through-hole components for the end user to solder to complete the kit. I know this has been done in the past with certain electronics kits of dubious legality. Technically, you're selling something that is totally non-functional. It's up to the end user to turn it into an actual working device - even if it's only by soldering in a resistor or two.
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an update for the cano arduino personal decoder.....
it's time to make the PCB ! a picture of the cano shield..... http://img.imagesia.com/fichiers/cg/...cgfk_large.jpg Abstract for the personal decoder : 1 arduino leaonardo board 1 ethernet W5100 shield 1 cano decoder shield 1 TP link nano router 1 loop with jack terminal 1 battery (lipo 2S) the decoder is wifi connected to a smart phone with android.... |
Originally Posted by luluFRA
(Post 12630998)
an update for the cano arduino personal decoder.....
it's time to make the PCB ! a picture of the cano shield..... http://img.imagesia.com/fichiers/cg/...cgfk_large.jpg Abstract for the personal decoder : 1 arduino leaonardo board 1 ethernet W5100 shield 1 cano decoder shield 1 TP link nano router 1 loop with jack terminal 1 battery (lipo 2S) the decoder is wifi connected to a smart phone with android.... |
Originally Posted by luluFRA
(Post 12630998)
an update for the cano arduino personal decoder.....
it's time to make the PCB ! a picture of the cano shield..... Abstract for the personal decoder : 1 arduino leaonardo board 1 ethernet W5100 shield 1 cano decoder shield 1 TP link nano router 1 loop with jack terminal 1 battery (lipo 2S) the decoder is wifi connected to a smart phone with android.... Sweet!! |
Hi
I have been looking into the possiblities of making an AMB type of timing system that does not use IR, has powered transponders with a loop in the ground, and allows for at least eight races per race. The threads on this forum, have some members that have realy been doing great work on building there own type of systems, and I thank them for sharing this info with others. I know that the systems that have been made work..... but is there one that works similar to an AMB, it transponders do not have to work with am AMB system. I was really keen on buying a system from Speed Transponder, but this system's software is in German, which would not work for our english speaking club members. I am therefore looking for info to buy or build a similar system to the Speed Transponder system..... any help would be appreciated. |
Originally Posted by garycapetown
(Post 12675448)
Hi
I have been looking into the possiblities of making an AMB type of timing system that does not use IR, has powered transponders with a loop in the ground, and allows for at least eight races per race. The threads on this forum, have some members that have realy been doing great work on building there own type of systems, and I thank them for sharing this info with others. I know that the systems that have been made work..... but is there one that works similar to an AMB, it transponders do not have to work with am AMB system. I was really keen on buying a system from Speed Transponder, but this system's software is in German, which would not work for our english speaking club members. I am therefore looking for info to buy or build a similar system to the Speed Transponder system..... any help would be appreciated. |
2 Howard - yes, you was right. Changing amplifier loop was successful. Our guy add some capacitors and switch to change them on fly. Now we able to tune amplifier to loop regardless of its length.
Next week we will have big indoor ivent, so I think we'll have big statistic about work our decoder with short loop and different chips - Howard, amb, may be mrt. |
Thanks for your reply maeg,
I know that the transponders work with AMB as well. How long have you made your loop? Our track is 10m wide, so the loop wire will have to be 20m long. Howard, Would the amplifier and decoder be able to work on such a long loop? Is anyone already using the system sucsessfully with such a long loop? |
Originally Posted by garycapetown
(Post 12682023)
Thanks for your reply maeg,
I know that the transponders work with AMB as well. How long have you made your loop? Our track is 10m wide, so the loop wire will have to be 20m long. Howard, Would the amplifier and decoder be able to work on such a long loop? Is anyone already using the system sucsessfully with such a long loop? |
I agree with maeg. 10m is far too big. That's about twice the original design limit.
|
2 garycapetown
You don't need to do loop on widest part of track - take it to the one of tight turn. |
The thread has reached another milestone. We now have more views than the very widely-read thread complaining about "AMBrc's overpriced transponders".
|
Do we have a CLPD yet?
And if we do can I get a copy of the programming or a chip. I can hand solder most surface mount devices over .05 but prefer .08 64pinTQFP. I have been watching this project from day one and I am really impressed with the progress. At one point I was thinking of using a Xmega for the decoder but even at 48Mhz and in machine language the Xmega would be to slow and the TTL chip solution is a great idea but to big for my taste. The CLPD is the way to go ,I would rather spend $25.00 for one chip then point to point solder 15+ chips. The Arduino shield is a neat idea for Hobby level designs but I would rather develop my own hand held timing system in a 2 chip solution that would output AMB compatable packets. then I can use one of the many timing systems that are out there. |
Originally Posted by Skruger
(Post 12703433)
Do we have a CLPD yet?
And if we do can I get a copy of the programming or a chip. Later this year I'll be implementing the whole thing in an FPGA with multiple channels, event timestamping and data buffering. First I'm trying to simplify the input amplifier. |
Originally Posted by howardcano
(Post 11897815)
Here’s the schematic I promised earlier:
The microprocessor receives transponder data (stripped of the first two bytes by the Preamble Detector / Stripper, or PDS), timestamps it, and transmits the result as ASCII hexadecimal characters in asynchronous serial format to an external computer. (Alternatively, I have also created software that recognizes a single transponder and calculates lap times for it, for use in testing and as a “Personal Lap Timer”.) Microprocessor U60 runs at 20 MHz, as determined by crystal XTL60 and capacitors C65 and C66. (U60 is shown as a 28 pin PIC16F886; my prototype uses the 40 pin PIC16F887.) One of the internal counters runs at 32.00 KHz, as determined by crystal XTL61 and capacitors C67 and C68. This is used as a timebase for the timestamps. U61B divides the 20 MHz clock down to 10 MHz for use in the Synchronous Serial Converter (SSC). (Thanks to Brano, “OM2KW”, for pointing out that the PIC oscillator will drive the counter when in HS mode.) The prototype currently transfers the transponder data into the microprocessor using the components labeled “Parallel Interface”. When the code for the SPI interface is complete, these will be eliminated , and U61A and U41D will serve the purpose. http://i1191.photobucket.com/albums/...psc84c6d9c.jpg EDIT: For the latest schematics, see post 206: http://www.rctech.net/forum/12118142-post206.html Is it possible to give the SPI signal characteristic ? number of bit, parity, SPI mode, clock polarity, data is capture on clock's rising edge or falling edge ? Thanks. |
Originally Posted by luluFRA
(Post 12853556)
Is it possible to give the SPI signal characteristic ?
number of bit, parity, SPI mode, clock polarity, data is capture on clock's rising edge or falling edge ? Thanks. http://www.rctech.net/forum/radio-el...l#post11880840 Data should be captured in on the positive-going edge of SSCLK, or the negative-going edge of /SSCLK. The schematic you show was for a previous hardware revision, which created a slave select signal and gated clock for the PIC microprocessor. In this case, data should be captured on the positive-going edge of SCL. There is no particular number of bits. The bits are presented serially with no delays between bytes, words, or any other groupings. The data stream will continue as long as valid data is received. Since there is no particular grouping of bits, there is also no parity bit. It is up to you to determine what operating mode on your microprocessor will support the data stream presented to it. On a related note, I recently heard from Microchip regarding the problems I had with their SPI module. I had previously posted that I could not get their module to work when running at the maximum serial clock frequency specification, despite all timing requirements being met. Microchip has confirmed the problem. I'm sure it will take a new silicon revision to fix it, but I don't think that's in their agenda, since the current silicon has existed for quite a while, and I was the first one to report the problem to them. |
Hello Howard!
Our winter season is in hot time. Could you explain, please, about capacity of loop? We have some problems with signal quality, Payalneg added to the firmware option to display signal quality for each time it detects transpoder - so now I can see it on track in real time. I need to tune my loop better. The only thing I can try - is changing wire of the loop and capacity. Maybe some rules for changing capacity? When I need to take bigger capacitor or smaller? |
Originally Posted by maeg
(Post 12900707)
Hello Howard!
Our winter season is in hot time. Could you explain, please, about capacity of loop? We have some problems with signal quality, Payalneg added to the firmware option to display signal quality for each time it detects transpoder - so now I can see it on track in real time. I need to tune my loop better. The only thing I can try - is changing wire of the loop and capacity. Maybe some rules for changing capacity? When I need to take bigger capacitor or smaller? http://www.rctech.net/forum/12222187-post251.html In general, a larger loop will require less capacitance to keep it resonant at about 5 MHz. You can verify that the tuning is correct by monitoring the output of the loop amplifier (R11 pin 2) using an oscilloscope with AC coupling. Place a transponder above the center of the loop, high enough to reduce the loop amplifier output to about 10mV peak to peak, then adjust the loop capacitance for maximum carrier output. |
Thank youm Howard.
If I only have an oscilloscope:) Now I can see if it is OK or not only by Signal Quality displayed at decoder, but rule large loop less capacity is what I was need:) |
I have encountered the same problem two races in a row now... Everything works great all day long and then at about the 11-12th hour of my race program... Mylaps RC4 Decoder box is not taking in anymore laps. If i reboot the box it starts working again... I have been tempted to clear passing on the box but figure it would be much better to ask here- I really only mess with the squelch on the box-
What is going wrong... Also what if any maintenance to the box is needed? Thanks guys! |
Originally Posted by notch johnson
(Post 12930326)
I have encountered the same problem two races in a row now... Everything works great all day long and then at about the 11-12th hour of my race program... Mylaps RC4 Decoder box is not taking in anymore laps. If i reboot the box it starts working again... I have been tempted to clear passing on the box but figure it would be much better to ask here- I really only mess with the squelch on the box-
What is going wrong... Also what if any maintenance to the box is needed? Thanks guys! The disadvantage in posting here is that this thread is not about the RC4 decoder, so you may not get many responses. |
Originally Posted by howardcano
(Post 12682318)
I agree with maeg. 10m is far too big. That's about twice the original design limit.
I could see potential interest from other forms of racing (ie. auto, motocycle, etc) if the loop could accomodate greater lengths and transponders could send greater distances. |
Originally Posted by RollnThndr
(Post 12988179)
Myself being an electronics novice, I need to ask, would it be a huge design change to get longer loop lengths?
I could see potential interest from other forms of racing (ie. auto, motocycle, etc) if the loop could accomodate greater lengths and transponders could send greater distances. Increasing the transponder power requires a new output circuit, but the only technically challenging part of that is emissions compliance. This would, of course, require a new PC board. |
@notch johnson:
I have experienced in the Cano-design almost similar things: After sundown, the loop picks up a lot of environmental RF-signals. This is known from shortwave communications were sgnals travel much further during the night. Worldwide communications advantage from this fact. Normally you will not notice additional HF signals (around 5MHz) captured in the loop because the preamble-word needed to decode a valid transponder-ID is not met. The noise received from the sky after sundown has a random character. However I have added from the start of my experiments a monostabil multivibrator (1/2 74123 TTL) that is set to 100mS and controls a green LED by a transistor. The input is connected to the Valid-signal of the decoder. The LED blinks every time a car passes the loop. But also when environmental HF noise matches the set preamble word. To my surprice, after sundown the green LED is much more active compared to the situation during the day. Most passes of a car are still detected (they are send average every 3mS), but I still wonder whether others notice some degredation of sensitivity. @notch: Could you try to start a test where the 11 - 12 hours of usage ends well before sundown to prevent the above explained to decrease the receiver sensitivty? Thank you! |
Detection loop noise
Hey guys, I hope this isn't too off topic but I'm looking for some help and you'll seem like you might have my answers :-) (I hope!)
I just installed an indoor carpet track in my shop with an RC4 decoder. The coaxial run is approximately 30 ft long (copper shielded wire). The detection loop is 1 ft x 5 ft. The noise level on the coaxial by itself is around 9 to 10. The noise level on the whole system with the detection loop connected is around 70 during the day and as it gets later in the evening sky rockets to about 150. I have mounted the detection loop on a piece of cardboard and moved it around the room and up and down with no real difference in the noise floor. During the day, the noise is not a big deal because the signal from the cars is close to 100 points over the noise. But by 7 to 8pm, I'm concerned that the signal to noise ratio will not be great enough to ensure accurate readings 100% of the time. Is there any way to shield the loop, or anything else to minimize the noise introduced to the system? Thanks a bunch for your help! Shannon |
Originally Posted by Only Fine Helis
(Post 13057198)
Hey guys, I hope this isn't too off topic but I'm looking for some help and you'll seem like you might have my answers :-) (I hope!)
I just installed an indoor carpet track in my shop with an RC4 decoder. The coaxial run is approximately 30 ft long (copper shielded wire). The detection loop is 1 ft x 5 ft. The noise level on the coaxial by itself is around 9 to 10. The noise level on the whole system with the detection loop connected is around 70 during the day and as it gets later in the evening sky rockets to about 150. I have mounted the detection loop on a piece of cardboard and moved it around the room and up and down with no real difference in the noise floor. During the day, the noise is not a big deal because the signal from the cars is close to 100 points over the noise. But by 7 to 8pm, I'm concerned that the signal to noise ratio will not be great enough to ensure accurate readings 100% of the time. Is there any way to shield the loop, or anything else to minimize the noise introduced to the system? Thanks a bunch for your help! Shannon Don't be afraid to start a new thread to get help! There are many knowledgeable people here on RCTech, and I'm sure many will have good advice. But you may not reach those people on this particular thread. Forgive me for pointing out the obvious, but have you asked MyLaps for advice? I'm curious to hear their response. |
Thanks Howard,
MyLaps response was basically to get the loop away from metal and devices conducting electricity. Given that I have moved it all around the confines of the room that it is in, I'm kinda stuck. I asked them about any kind of gain settings (not squelch) and they weren't of much help there. One of the guys was going to their headquarters in Europe this weekend and he was going to ask the tech guys over there about it and let me know. Thanks again, Shannon |
Thanks Howard!
Here is my decoder smd components, made by the scheme Howard. _h ttp://rc-auto.ru/forum/index.php?act=Attach&type=post&id=31599 |
Loop Amplifier
h ttp://rc-auto.ru/forum/index.php?act=Attach&type=post&id=31600 I can not spread links, posts a little. |
They look great! Here are the photos:
http://i1191.photobucket.com/albums/...psd20f6174.png http://i1191.photobucket.com/albums/...psd20f6174.png |
BPSK coding
I was looking at the BSPK signal to figure out the encryption. Is this information available ?
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I finished the decryption protocol coding AMB
http://cs606519.vk.me/v606519346/54e3/bXiwveI7puk.jpg |
Originally Posted by Payalneg
(Post 13157162)
I finished the decryption protocol coding AMB
http://cs606519.vk.me/v606519346/54e3/bXiwveI7puk.jpg |
convolutional codes and the Viterbi algorithm
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Originally Posted by Payalneg
(Post 13157304)
convolutional codes and the Viterbi algorithm
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I was thinking about an RPi this before reading this thread. Great minds think alike. Im not a coder, but I would think a SDR receiver like the USB dongles found on ebay could work for decoding. I know some of them work for digital radio receiving on the ham bands for PSK31, etc.
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Originally Posted by StHanley
(Post 13166236)
I was thinking about an RPi this before reading this thread. Great minds think alike. Im not a coder, but I would think a SDR receiver like the USB dongles found on ebay could work for decoding. I know some of them work for digital radio receiving on the ham bands for PSK31, etc.
There are circuits in this thread which use a microcontroller to timestamp the data, these get good enough precision. Moving all decoding and timing to an FPGA (with averaging of multiple hits) gets both accuracy and precision even closer. Then there's the fancy analogue magic that AMB use (probably patented) that will get you the last bit of accuracy. The Raspberry Pi is a great device but a normal operating system isn't going to get you accuracy or precision. You'll still need all of the decoding and timestamping to happen in a dedicated circuit. Lastly many of the RTL SDR devices are designed as TV tuners (for DVB-T). These generally wont be able to tune low enough to get to 5Mhz-10Mhz. Even the HackRF (designed from the ground up as an SDR) isn't rated below 30Mhz. |
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