Running Ground Mats / Antennas DIY

[Jon Agriesti]

Hi Group,

Has anyone tried to make their own ground antennas (mats) for RR / XC races? My thought was to use cord ramps on the ground with impinj threshold antennas inside of the ramps. Three ramps, three antennas would make a good size finish line. 

Looking at Chronotracks timing mats, that is basically what they are. 

Any thoughts or ideas from the group on DIY mats?

Looking forward to ideas.

Jon

[Patrick W]

That's basically what the first gen race results, trident, and a couple other mats were - threshold antennas inside ramps.  You can't go for the cheap ramps because you need to resist slide on surfaces, so you need the weight that tends to come with the better quality ones.   I thought about rolling my own, but by the time you buy the antenna, cables, and ramps you might as well just get the package because it's not much cheaper, and the commercial version is more water resistant.

[Springer Sport]

Hi Jon,

I recommend you the following thread:
https://groups.google.com/g/agee-race-timing/c/mcdjMbne3Js/m/SC8Oh-I2CgAJ

Martin

[Oscar Wagner]

Chronotrack's Impinj mat antenna system is so sorry that almost NONE of their reads come from the mat antennas.  Their REAL bib tag read system is chest high side mounted "FlashPoint" antennas.  Guessing these proprietary antennas (about $1800 EACH) are "dual frequency" / constant output and constant input.

With two sets (4 Flashpoints) across a 58' street (I measured the course) they got 98% of the chip starts at a cheek by jowl 4,000 person race last Thanksgiving. Be nice if someone could engineer us something cheap and similar.

    
My standard for read speed is an FX7500 (30% faster than a 9500 which I hear is faster than a 9600) using ONE PORT (NO multiplexing) and a vertically oriented YAGI linear antenna using vertically oriented R-6 Dogbones  (no time wasted on poor % reads in horizontal direction).  Anybody know anything faster without going to full duplex / dual frequency antennas?

OSCAR

[kevin plummer]

I am looking at doing the same thing but making my own antennas up using a micro patch antenna mounted on an aluminium ground plane to increase the DB and hence range. Maybe 4 or 5 antennas in each section of cable protector.

I have ordered my first Micro Patch Antenna to have an experiment with before I try and advance further, I haven’t a clue whether it will work but for £6 to start with it won’t be the end of the world if I throw it in the bin. What are your thoughts? I am very much a newie to all of this. 

  Image 1 - Circular Polarization Antenna UHF RFID PCB Components 902-928MHz RF Range

  

[Jon Agriesti]

Thanks everyone for the information. That is what I was looking for. With Fiebot patent issues and RR being so expensive, plus still have shipping issues, I was looking for alternatives. 

[Joe Fertsch]

Hey Guys - Just giving my 2 cents.  I have multiple race result mats and fiebot mats.  Looking at my reads and most recently using the new antenna dashboard on ART rfid screen, I realize how much better side antennas are performing compared to even expensive RR mats.   I am now going with 2 over head antennas within inflatable arch and two on the side and getting much better reads without the need for a mat.   I still have my mats but when you compare to well placed panel antennas I am going against mats.  I am not sure if anyone else has noticed this.   Also 4 well positioned panel antennas are probably more efficient compared to 8 mat antennas in my opinion  

[Springer Sport]

Hi Joe,

But you should also consider the cost-benefit ratio. Over head antennas require trusses and trusses also costs money. But the truss has to be constantly erected and dismantled, which means much more transport, time and work. In the end, it's not about how often the participants are detected at the finish line, but that all participants are detected. In my experience, the ground antenna(s) ensure this.

[JK Race Timing Systems]

 " Also 4 well positioned panel antennas are probably more efficient compared to 8 mat antennas in my opinion "

Do you mean into 1 reader or 2 readers, If 1 reader I would agree, An 8 mat system into 1 reader is a waste of time.

Mat systems are very good if done correctly, you should be able to tell how good your mat system is doing from your success rate at the chip start( count how many athletes have a gun and chip the same), any more than the first elites on the start line and it means they arent being picked up.

Mats do have their place, Im not a fan of them at the finish from a trip hazard point of view only, and the fact that I went with gantry from day one so it is normal for me,

A simple error timers seem to make with mats can have the worst effect, Know your multiplex sequence and connect your antennae in accordance with that so that you do not sweep from left to right or vice versa,  a load of reads will be missed in a setup like that.

I made a set of diy mats recently out of old alien linear antennae and I am flabbargasted at how good they work. DEfinitely as good as the impinj threshold linear antennae ( at 440 euro a pop)

Best regards

JK

[Springer Sport]

Hi JK,

because I time rarely events with a timing line at the start, I can't say much about the failure rate with very dense participant fields. At the finish line, my ground antennas are working very, very reliably. Of course, I am aware that the switching time of the multiplexer should be as short as possible and the individual ground segments should not be connected in series so that no area remains unread for too long.

You got me curious: what exact type of older alien antennas do you use in your ground mats?

Regards, Martin

[Gregg Mrkvicka]

"A simple error timers seem to make with mats can have the worst effect, Know your multiplex sequence and connect your antennae in accordance with that so that you do not sweep from left to right or vice versa,  a load of reads will be missed in a setup like that."

Can you please expand on this? Should I be attaching antennas to the reader in a specific order?

[Springer Sport]

@Gregg: Maybe I should have gone into the basics a bit more: many timers believe that all ports of the reader are read at the same time. This is wrong! Each antenna port is scanned individually and there is a switching time from antenna port to antenna port (approx. 250 µs for the Impinj Speedway R420 or approx. 8 ms for the Feig ID LRU1002). Sometimes shorter switching times can be achieved with an external multiplexer (e.g. less than 1 millisecond with Feig ID ANT.UMUX).
If the antenna segments of your ground antenna are all scanned one after the other from left to right or vice versa, the temporal reading distances will be greatest. However, if the antenna sections are read in a thoughtful order, no section of the antenna will remain unread for any length of time.
Please consider that the duration of the reading processes of other transponders must be added to the switching times of the multiplexer.

[Springer Sport]

Hi Gregg,

Here is an example with 4 antenna segments in a floor mat:

Reader port 1 - antenna segment 1
Reader port 2 - antenna segment 3
Reader port 3 - antenna segment 2
Reader port 4 - antenna segment 4

Here is an example with 8 antenna segments in a floor mat (...but only in connection with ONE reader!):

Reader port 1 - antenna segment 1
Reader port 2 - antenna segment 5
Reader port 3 - antenna segment 3
Reader port 4 - antenna segment 7
Reader port 5 - antenna segment 2
Reader port 6 - antenna segment 6
Reader port 7 - antenna segment 4
Reader port 7 - antenna segment 8

This will ensure that no area of the mat is left unread for too long.
If you use two different readers (e.g. two 4-port readers) it would be fatal to connect the antennas mixed!

Gregg Mrkvicka schrieb am Donnerstag, 14. Juli 2022 um 17:30:23 UTC+2:

[Patrick W]

This really is what it's about.  The high level theory is that you want your reads in a pattern that keeps the previous, current, and next read segment both spread out over the whole mat, but also as close to each other, so that the next read segment still has a higher chance of catching a missed beacon (since the tags will typically beacon once or twice after the power is switched off to the segment it's closest to).  It is a weird concept to explain because it is somewhat a "radio is magic" thing as well, so you may find different patterns work better for your specific use cases than what others find work for them.

[Raphael Leal]

Do you recommend that same setup if I use 2 side panels + 2 floor mats?

[Springer Sport]

@Raphael: If you connect all 4 antennas to ONE 4-port reader you can use exactly this setup. It is really important not to use this setup with two different readers!

If you are working with two different readers, you should use the first reader at the finish line and some metres behind the finish line the second reader as backup.