Electronic Monitoring Feasibility Check Failure

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nullmee

53 posts

Master Geek

#268165 2-Mar-2020 21:56

Hi all,

I am hoping someone in this forum would be able to help clarify a recent failure during a feasibility check for GPS electronic monitoring. This was undertaken for a person who is seeking home detention for a case in a district court.

This same address that has failed the feasibility check was used previously 6 years ago, with a number of the neighboring properties also being used in a past few years. There are increasing reports of this happening in rural parts of the country, and a new provider has in the last year taken over the national contract providing this service.

The results show the the GPS tests failed inside the property, and the RF tests failed outside the property at a number of locations. I have the test results available if this is required, the carrier is listed as Vodafone

The location of this address has mobile coverage with both Spark and Vodafone, is in a rural town of around 400 people in Northland.

If someone could please help us understand why this address has been used previously with no issues and now is failing the feasibility test that would be greatly appreciated.

Thank you

andyb

236 posts

Master Geek

Trusted

Spark NZ

#2431692 3-Mar-2020 11:43

I would say you are best placed to have a talk with Vodafone.....

andyb

frankv

5680 posts

Uber Geek

Lifetime subscriber

#2431698 3-Mar-2020 11:57

"GPS tests fail inside the property"... are you saying that within the property, presumably a farm, you can't get GPS positions? That seems extraordinarily unlikely. With modern GPS units, even in a deep valley or under tree cover, you usually still get enough signals to get a location. I'd suspect that there's some kind of (probably deliberate) interference with the signal, either covering the receiver with e.g. tinfoil, or some kind of jamming.

I'd be interested to see what the GPS test results show.

chevrolux

4962 posts

Uber Geek
Inactive user

#2431714 3-Mar-2020 12:24

You would assume the test fails on uploading the GPS result, not actually get a fix.

Sounds like VF just have a different coverage footprint to Spark. Shock horror!

It seems short sighted to award the contract to a single supplier for something like this. You expect the individual to be mobile so you would think a dual SIM approach would be far better.

nullmee

53 posts

Master Geek

#2431813 3-Mar-2020 13:59

frankv:

"GPS tests fail inside the property"... are you saying that within the property, presumably a farm, you can't get GPS positions? That seems extraordinarily unlikely. With modern GPS units, even in a deep valley or under tree cover, you usually still get enough signals to get a location. I'd suspect that there's some kind of (probably deliberate) interference with the signal, either covering the receiver with e.g. tinfoil, or some kind of jamming.

I'd be interested to see what the GPS test results show.

Yes seems strange to me as well. BTW it isn't a farm it is in a little township which is a peninsular with the Vodafone tower being across the harbor on the other side of the peninsular. You can still get Vodafone coverage but it is not as strong as the eastern side

Please see test results below, have removed any personally identifiable information:

Global Positioning System [GPS] is used to monitor compliance with Home Detention, EM bail and when a person has a wherabouts condition. Radio Frequency [RF] is used to monitor compliance with Comunity Detention.

The test result shos that GPS failed at the property GPS Doanload not received
Failed [GPS DL Not Recd Fail]
Radio Frequency [RF passed inside the property but failed at four of the five external points.

Test Results:

Message:
Carrier: Vodafone Letter Box 2G dBm - 107 3G dBm - 107
Equipment Nos. RF TX: 406429 RF HU: 109818 GPS TR 34303748 34308113
RF HU Located Lounge Table GSM Bars 3 RF Range setting (medium)
1st RF Doanload 1m 44s Pass
GPS DL Not Recd Fail
GPS DL Not Recd Fail
Internal:
Kitchen/Lounge RF Beeps 4 pass
Bathroom/Toilet RF Beeps 4 pass
OD Bedroom 1st on RHS RF Beeps 4 pass
Bedroom 1st on LHS RF Beeps 4 pass
Bedroom 2nd on LHS RF Beeps 4 pass
Laundry RF Beeps 4 pass
External:
1st Corner Front Left RF Peeps 0 Fail
2nd Corner Front Left RF Peeps 0 Fail
3rd Corner Front Left RF Peeps 0 Fail
4th Corner Front Left RF Peeps 0 Fail
Garage RF Beeps 4 pass
Result: RF Feasability completed

Zepanda66

533 posts

Ultimate Geek

#2431823 3-Mar-2020 14:25

Could there be something nearby that wasn't there 6 years ago thats causing interference and resulting in the signal failing? Maybe like a power station or something thats on the same frequency as the GPS?

http://www.speedtest.net/result/7315955530.png

xpd

Geek @ Coastguard NZ
13766 posts

Uber Geek

Retired Mod

ID Verified

Trusted

Lifetime subscriber

#2431831 3-Mar-2020 14:33

chevrolux:

It seems short sighted to award the contract to a single supplier for something like this. You expect the individual to be mobile so you would think a dual SIM approach would be far better.

Yeah, we had a neighbour years ago who had a "bracelet" - was allowed out between 7am and 7pm.

But when was at home outside of those hours, he was restricted to his bedroom, toilet and hallway. Couldnt get signal anywhere else in the house. He was just happy that there was a power point in the hallway so he could still make a decent coffee throughout the night :)

This was on the North Shore, albeit in a valley.

Dual SIM/supplier wouldve been ideal for him, as Spark had decent coverage in the same area.

Gavin / xpd / FastRaccoon / Geek of Coastguard New Zealand

LinkTree

frankv

5680 posts

Uber Geek

Lifetime subscriber

#2431834 3-Mar-2020 14:40

Looks to me like it's not GPS per se that's failing... it's the download of the GPS tracking data that's failing. Which is likely a problem to raise with Vodafone.

NB: Years ago I went to a presentation by a guy who was involved in the very first cellular rollout in Auckland. He commented that setting cell sizes was difficult, because the signal strength was affected by the depth (or maybe presence, it was a long time ago) of water over which it was transmitted, and Auckland's water is largely tidal. So what worked well at one point in time didn't work well 6 hours later.