the itrip from hell

Noise and interference issues?
Post Reply
Tim Bucknall
Posts: 2345
Joined: 01 Oct 2014 14:55
Location: Now stranded in Congleton
Contact:

the itrip from hell

Post by Tim Bucknall » 13 Sep 2018 16:33

radiating not only on the intended channel but also fully modulated but unstable carriers
112khz either side , almost as strong as the fundamental

https://mega.nz/#!opEAQIDD!fl_SpUr580kO ... EQv2NJdLss
Home:Burkhardt Reuter RDR54D1 SDR V.415,
+ CLP 5130 Log P ant

Mobile: Comm Radio CR-1 + Sharman Skyscan ant, Pira P275

bristolpirates
Posts: 45
Joined: 22 Jul 2015 20:31

Re: the itrip from hell

Post by bristolpirates » 22 Sep 2018 07:41

Stange that the spurious carriers move opposite to each other, like mirror images.

Why have iTrips gotten so strong and so common in the last couple of years or so? I guess the legal versions stopped selling because they are a little too underpowered, and people get any old TX off of ebay instead, thinking it's legal?

The first strong one I encountered is still on air most of the time, two/three years later. It's in a flat about 10 mins walk from my house. The person uses it to broadcast TV sound to their Hi-Fi as far as I can tell.

Since that appeared, more and more I can watch the bottom of the band for an hour or two and will be likely to find one as it drives past.

There is one that comes and parks up in the social club car park at the bottom of my road every Thursday night. There's been on on 107.0 for the last couple of days, parked somewhere near.

I wouldn't mind if they were being used and putting out something interesting, but it's mostly blank stereo carrier, which is just irritating. So, these things don't even switch themselves off any more.

daveB
Posts: 1246
Joined: 07 Oct 2014 16:49

Re: the itrip from hell

Post by daveB » 22 Sep 2018 10:06

The one that plagues me is centred on 89.0 MHz and has spurious carriers that spread +/- 3 MHz, or more. Fortunately the owner of the vehicle has got into the habit of switching it off when they leave the car - after I mentioned to them that I'd tracked the interference down to their car.
SDRPlay, AirSpyMini, RTL dongles, SB920s, Yamaha TX930. 5 ele compact yagi on rotator at 18ft agl. FM5 facing east, FM5 facing south, FM3 facing NE, OIRT dipole, 3-ele Moxon vertical facing east.

Tim Bucknall
Posts: 2345
Joined: 01 Oct 2014 14:55
Location: Now stranded in Congleton
Contact:

Re: the itrip from hell

Post by Tim Bucknall » 28 Sep 2018 10:35

nice one Dave!

trouble is the unlawful models are cheaper than the legit ones and , if my experience is anything to go by, more reliable.
i've owned 3 units in the past ,
market stall model with choice of 106.7, 107.1, 107.3,107.5 - none of which are really useable in North Staffordshire & South Cheshire any more
chinese ebay model that did 4 miles out of the box (unmodded tx running at home on aaa batteries , received on car rx on a hilltop)
i gave it to JF for his medium wave dxpeditions so he could listen to perseus audio on the car system

when i did make a point of looking for a legal one for distance tests (belkin) it burned out and made a funny smell the first time i turned it on.
that was 3 or 4 times the costs of the other units mentioned


south of me my house backs on to what was formerly my old school but now a housing estate.
south of that is traffic lights on a main road (A54) i hear cars stopped there but yeah mostly blank carriers or kids programming on 87.5-87.7 & 108
the interesting px were so rare i can actually remember them, someone running down the us country chart and a programme about flora & fauna in australia


i assume the high quality ones with RDS (always on 87.6) are within legal limits?, i'd like to have a play with one of those!
i'm not sure if the in car txs have got stronger here but i hear a lot of home txs that are obviously overpowered relaying tv sound, theres one who broadcasts radio 4 time shifted by exactly 3 hours they're way off freq like 87.660, 87.75

whats legal power? the spec gives the permitted strength in units i can't get my head round, i need it in mW
i wondered if the original i trips were designed around the US part 15 regs then accepted into euro law?


i remember when the old editor of practical wireless rob mannion claimed there were young people in cars driving round his town with 200watt txs !
first of all, how could he know? and secondly that much juice would require a direct connection from the car battery , not just a cigar lighter socket

i eventually figured out the M.O after reading a few other issues of PW. every week he would create a big new scare about an imaginary new interference source (while ignoring the real qrm sources mind!)


one sunday a month or so back it seemed like everyone and his dog were txing, it was kind of fun to hear, i'm all for it
the US part 15 law gets it right imo

i see similar lp txs being sold in online German hi fi shops but for AM, legal? or have the authorities just given up on am?
i know there a few brits with spitfire txs


theres a tesco express near me and the car park is ground zero for
LPFMs, i park there to test different mobile fm antenna set ups, if i can capture full RDS on 87.6 from someones itrip (usually relaying talk radio, absolute, radio 5, 1 extra etc) on my pira P275 rds analyser i know the ant is working.

the most interesting content is probably Balkan Gypsy pop music on 87.5 from Romanian truck drivers


i want to break the ITrip distance record, txing or rxing!
Home:Burkhardt Reuter RDR54D1 SDR V.415,
+ CLP 5130 Log P ant

Mobile: Comm Radio CR-1 + Sharman Skyscan ant, Pira P275

Post Reply

Return to “EMC (Interference) Issues”