Impinj threshold antenna verdicts

[JK Race Timing Systems]

Hi
I have a chance to pick up a few of these antenna and would like to know if anyone else is using these. I have an upcoming race that will have runners passing close by the finishline twice before coming through and had some stray catches last year. I am looking for a sharper more controlled finish area. Are these a good option in practice

[Tim Irvine]

I had two when I first started. I eventually sold them to another timer. They worked fine. In fact, Chrono Track users use this antenna a lot too. I sold mine because I wanted (at the time) to do more truss antennas. Funny how priorities change over time. Make sure the tags are on the bibs vertically and I think you will like them. Tim

[JK Race Timing Systems]

Hi Tim

Thanks for that.

It was just by chance that a dude was selling 4 of them on ebay and I offered a swop for a speedway R420 and he accepted.

Hmmm I normally hang my laminated tags vertically on the race bib but I aswell use an overhead gantry so my intention was to have the threshold antennas on the overhead ( following the line of the truss), would that mean that the polarity will be wrong or is that correct. I see they are linear polarisation but I cant figure out whether they are vertical or horozontal.

Thanks and regards

JK

[Tim Irvine]

Interestingly enough, I considered hanging mine on my truss too. I even fashioned a way to do it. Ultimately I chose to not do it. I do know the folks who use Threshold regularly have really good success with vertical shoe tags, or in the case of Chrono Track, D-Tags. That was why I was experimenting with my Lace tag idea. That worked too by the way. However, I have gotten tot he point where If I were still using Threshold, I would have those down under and two MTI's on top pointing down. If you decide to use MTI's overhead, I posted about my Lace Tags on a thread sometime back, but had photos of a mount I built that a lot of timers liked. 

[JK Race Timing Systems]

Thanks Tim,

Are you saying you would use then on the vertical uprights of the truss 

[Tim Irvine]

If you did use them that way, you would want to put the tags on the bib horizontal. Threshold across the finish on the bottom = Verical Tag placement. Threshold mounted on the tripods vertically = horizontal tag placement

[JK Race Timing Systems]

Update

The 4 antennae arrived this morning so I will do some intensive testing with these little beauties and report back.

Little beauties is literally correct. They are 18 inches wide by 2 cm thick by about 4 inches wide. well, well built heavy things. Only con to date is that it has a small SMA connector which will be promptly changed to the standard connectors I have on my cables.

I am hoping that these 4 will replace ALL my patch antenna on my trussing but only intensive testing will confirm this.

It is also my first real step into Linear polarisation, 

Test Test Test

regards

JK

[Peak Performance Timing]

Keep us informed of your findings.

[SNRyan]

I use threshold antenna (antennae ?) exclusively and love them. Extremely powerful, but remember they are linear so place the tags vertically. I double tagged one race since the arch that was supposed to be used was wider than my normal setup and would require a single line. Was getting most reads a couple feet before the "actual" finish line. See pictures.

[JK Race Timing Systems]

Excellent stuff.
The blasted adapters that I ordered to convert sma to my cables are wrong so I got no testing done today.
Are you using 2 per mat in your examples. I.e 4 Impinj antennae in the first pic and 2 in the second ?.

[Peak Performance Timing]

Excellent! Which cable guards are you using and where can they be procured?

[SNRyan]

JK - 4 total in all pics. 2 x 2 in the first and 4 across in the second. In my initial tests, about 1-2 feet off of the cable protector's edge is where I was seeing significant drop-off in tag reads with a bib on the stomach so I would not advise trying to use one antenna to pick up more than a 3 ft. section side to side. I was also using some spare tags from Brian in my tests and not the Dogbone so that distance may be expanded a little, but I wouldn't count on it. 

Peak - They are the 5 channel low profile Checkers Guard Dog that I found on Jet.com. They aren't custom so I had to cut out the channel dividers to fit the antenna. A bit of a pain but doable with a Dremel. Would like to have the ADA ones but for some reason the cost is double for that model.

[Tim Irvine]

SNRyan,

   Did your Guard Dogs mats slip? I have some too and mine slipped because like you I did not spring for the ADA ones. However, I bought some friction tape at Lowes or skid tape. and put cheap rubber mats under them and no slips at all.

[Hronometar]

Here is another solution, but these cable protectors are not cheap too. You can read my post in this thread.

In the post I wrote that Race Result was using Adam Hall Nano cable protectors for their ground antennas. If I am not wrong, it was until end of 2015. Here is RR video with a setup of their old mats. You can see their old mats in this video as well.

All details about Defender Nano cable protectors you can see here. I use them to protect my 400 series cables because I am not a fan of truss to use it for cable protection.

Still didn't patented my Nano + Impinj Threshold antennas, but I have attached a few photos from another timer who has developed it. 

[JK Race Timing Systems]

Hi Tim

Got to use these antennae today fro a race and results were pretty poor.

I had a lot of missed reads.

Could I ask you a question. I wonder is it to do with the way I mounted them.

Are they designed to be isolated from everything I wonder.

I see no mounting holes or anything on them so I added a truss mount and connected them to the truss.

I am now beginning to wonder if the back of them are to be isolated from metalwork.

Are they only designed to be placed in Dog guards etc.

Should I be using Plastic Non conducting truss mounts I wonder.

I have searched online for impinj Threshold antenna mount kits but cant find anything.

Arrangement was 2 overhead truss mounted antenna and a single foam backed Dogbone R6 on the bib.

Should have been a breeze

Any help appreciated

regards

John

[rtspt.usa]

Pics of set up?
Those antennas are normally used as ground antennas placed in cable ramps.
What is their polarization?
How were they mounted?
Both would also affect tag placement position.

[JK Race Timing Systems]

Hi

Ill try and get a pic.

They were mounted the exact same way that they would be in a mat. Pretty much vertically aimed downwards across a truss with approx 2 feet between them.

Bib Tag vertically hung on the bib

Tested the antennae at home and they were promising

[rtspt.usa]

That's ok, I can visualize it now..
They technically are "threshold" but I too would think that it would work overhead.. perhaps the human head creates more of a blockage than legs.

One thing to note is that other systems that use overhead antennas use 18dbi linear panel antennas so they are pretty powerful.

[SNRyan]

Tim-

Yesterday was the first time the I've seen them slip and it was the second/backup mat. The runner was stopping, so his foot must have been at the right angle. Had people pushing strollers and a few Ansley's Angels finish and didn't have any slippage. Might take a page out of your play book and get some rubber mats to put underneath. What brand did you go with?I have seen some photos of timers putting duct tape on both edges too.

[Christian C.]

How high is your gantry? If installed on the ground they would only be 1m (3-4ft) away from the chip.

C.

[JK Race Timing Systems]

HI

About the same as that, 8 foot high so they would be the same distance from the chip if they were a mat setup.

No that definitely isnt the issue.

I tested these at home in the house and they had a good 10 foot range.

I am just going to have to rig the setup up fully and retest, Is the chip correct being fitted vertically when using these antennae is this formation

Best regards

John

[Tim Irvine]

SNRyan, 

   Just some cheap Lowes mats. I think they were 10 bucks each.

[JK Race Timing Systems]

Hi

Ok so I had a few hours spare today and so I set up 1 section of truss ( I normally have a duplicate 9 feet back with the second set of antennae for the second reader).

I set up the 2 impinj antennae on the truss pictured and the results from the test could not be better. 100% reads every single time. These antenna seem to work best when aimed directly down and the tag attached vertically on the running bib.

No matter how I tried to fail the system it simply wouldnt. I was most impressed running through the line and shielding the tag with both arms across( simulating the typical runner stopping his watch as he passes the line), Made no difference , read everytime, bunches of tags not an issue either.

So then I had to figure out what the hell went wrong that caused these to perform horrendously last week at an actual race and I think I have the answer.

I decided to attach the right antenna to the reader 1 and the left antenna to reader 2 ( I couldnt face into erecting the second truss) simulating 2 readers interfering with each other. The results were as bad if not worse as the day I did the race, terrible reads and complete blind spots where I could actually walk through with no read from either reader.

This is proof if ever it was needed that it is a big no no to have 2 readers fielding into the same area causing tag confusion.

My redundant ( second truss, which actually isn't redundant at all) must have been causing confusion even though I had the recommended 9 foot clearance but in reality I didnt because on these antennae I normally face them slightly toward the finish line.

I am so much happier with these now and from this testing they look unbelievebly effective.  Looking at the specsheet for these antenna they are linear but are called slot anttennas and propagate in a doughnut type field and it seem that having these tags come in at a knife edge( which would not be suitable for any other antenna) seems to be ideal for these which I suppose is the reason they are used in mats etc.

Anyway I will carry out another set of tests with my local running team to confirm my results but it looks like I will be losing the second reader .

I will report back with those results 

[Peak Performance Timing]

This makes me wonder......because I use two separate lines of antennas with two separate readers on two separate computers for every race with 100 percent reads on both systems. My antennas are Thinkify TAC-60s , Readers are FX9500s and trusses have a 3 meter separation. Maybe it is because you are using both readers on the same computer? Or maybe because your antennas have a higher gain?

[JK Race Timing Systems]

Hi
Yep pretty much same setup as mine on a normal day. I would have typically 3 antenna on first truss and 3 on the second separated by 3 meters and normally 100% read rate. Only difference is yes I feed them into 1 computer. I use all circular polarised antenna but these Impinj are clearly stronger fieldwise (dbi same).
You may ask why I am mucking with a system that is getting me 100%read rate.
2 reasons really .
The main 1 is that I want to try and eradicate placing issues. 2 runners coming in and the system placing them incorrectly based on which antenna picks them up first.
Second reason is I want to make the finish line tighter. Circular antennae capture points differ on different days,whether road is damp etc. That is why I am testing.
Third reason to tighten up the finish line is because I have a town night race coming up where they pass very close (on laps) to the finish line twice before coming through to finish. The antennae I have used last year were intemittently picking up runners on their first and second lap and screwing the finish results. Results from today we're very promising in that regard.
As you know in this game testing is everything
Best regards John

[Oscar's Race Results]

I see the term "100% reads " a lot.  Does that mean that you always get at least one read per runner?  What is good for 3 guys in a pack doing a 5 minute pace approaching the line?  And that means  that on "final approach" they may be doing a 3 minute mile pace.  What do you expect in that situation?

[JK Race Timing Systems]

Hi
In a correct setup speed should have no part to play. when I was doing testing for a bike race I had a local cycling club cycle at full speed past a timing post in bunches and was getting easily 40 reads per cyclist (store rf Id option fantastic for that) so runners are not a problem at all.