UHF directional locator/tracker/beacon

[Shox Dr]

Has anyone experience of radio direction finders. I’ve a few items I’d like to pin point, one is my dog I take to work as some times she goes walk-about.
There are plenty of devices on the market for this, but they continually transmit.
There are also units for model aircraft/drones, that transmit after a set amount of time.
So far I can only find units that can be remotely turned on via TXT on contract. (£16pcm)

I’d like to either build a UHF transmitter or buy a unit. Then using a small GPS/SIM tracker (TK102) to switch on the beacon.


Any links, suggestions, comments

 

[Wendelspanswick]

My friend was using a RF dog tracker that he imported from America, he said it was brilliant to start with but has now gone back to using a cow bell on the dogs collar. I think the RF tracker was to cumbersome to use and unreliable.

 

[500e]

https://www.tuxedo-cat.co.uk/best-cat-trackers/

 

[Shox Dr]

https://www.tuxedo-cat.co.uk/best-cat-trackers/

Only 1 of those can locate via rf, and distance is limited.

The biggest problem I forsee is been able to turn the beacon on, hence the SIM module, at least (hopefully) a txt can be received by the beacon to turn it on via the TK103/4 out put signal. This would also give an approximate direction/area to start looking.
There’s a few vids on ut, with arundos and a rf transmitter but I know SFA about them

 

[Shox Dr]

This might fit the bill

https://tbeacon.org/?page=20&language=en&session=jengb0jr7m23c2b4smh22hb4d4

 

[AdrianH]

There are several gsm based vehicle trackers that are small and have internal batteries such as https://www.ebay.co.uk/itm/GF08-Min...UK/232979598975?hash=item363eaa8e7f:rk:1:pf:0

You can generally just get reports back to your own phone providing both are in coverage.

I use giffGaff sims that are reporting back every 30 seconds to 5 mins if no movement typical costs for them is 3p to 4p a day, no contract so about £1.50 per month use?

See a previous post on GPS tracking I did.

Adrian

 

[Shox Dr]

There are several gsm based vehicle trackers that are small and have internal batteries such as https://www.ebay.co.uk/itm/GF08-Min...UK/232979598975?hash=item363eaa8e7f:rk:1:pf:0

You can generally just get reports back to your own phone providing both are in coverage.

I use giffGaff sims that are reporting back every 30 seconds to 5 mins if no movement typical costs for them is 3p to 4p a day, no contract so about £1.50 per month use?

See a previous post on GPS tracking I did.

Adrian

I’ve a few myself. Problem is Cell, and GPS can be blocked. You cant block UHF

 

[AdrianH]

The sensitivity of these gps units is very good and do OK in my house near walls, but I would have thought a dog outside would not have that issue, same with gsm if dog is outside, unless you are in a bad area for gsm of course in which case turning the unit on would be an issue.

Is there an issue with people deliberately blocking signals?

Try searching for fox hunting kits one here available from US
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=400824562771&_sacat=0

Adrian

 

[atomant48]

Possibly the gubbins from a marine type personal locator beacon that you remotely activated. McMurdo fastfind is one of them. But they are vhf only (and 406) for some time now and you would need to tweak the transmit freq to stop setting hares running !

I assume you don’t want it “blocked” to stop someone stealing something but surely they just take a sledgehammer to it anyway ?

I’m also pretty sure UHF can be blocked (faraday cage? Spamming the frequency?) but not my area of expertise!!

Sounds like a fun project.

 

[Robbie260]

I’ve a few myself. Problem is Cell, and GPS can be blocked. You cant block UHF

Very easy to block uhf it dosent bend or reflect around objects like lower frequency wave carriers. Can easily stop uhf with a brick wall or a 15mm bit of steel we use uhf radios on ship signal gose nowhere un less we have a repeater station network installed or direct line of sight. You really would be wanting vhf but the best would be fm or am radio waves they can be hardly be blocked by anything.

 

[Shox Dr]

Is it not a big no, no. to use a marine repeater on land

 

[Robbie260]

Is it not a big no, no. to use a marine repeater on land

The ones we use onboard ship arent ship specific for uhf walkie talkies we use they are just like the one you would find in a big office block with security gaurds or manufacturing facility for maintenance team comunication. All it is is very small antena dotted about the ship they then collect the signals and relay them back to a central node which redistributes the signals to all the other antenas. Cant think why it be a no no to have on land. It is an offence to have a uhf or vhf radio with out a licence but individual ones its a one day course and exam and compaines can get collective ones to cover all the staff in thier employ i belive.

 

[Seadog]

Is it not a big no, no. to use a marine repeater on land

Yes. I've a marine handheld but licence conditions mean I can only use it on the water.

 

[AdrianH]

For unlicensed use you are really only talking about some of the very low power frequencies that are used by key fobs and the like, there are bands on 433 MHz and 173 MHz. But we are talking here of like 10milliwatt outputs with typically a poor antenna, but again the gear should be approved.

Adrian

 

[Wendelspanswick]

I've found that the likely places you'd lose a dog are the same places where there is little or no phone reception.
The Quantock Hills are a favourite location for dog walkers but terrible phone reception unless your on the periphery.

 

[Shox Dr]

Muttley is an example of the uses I have. Locating ‘Assets’ is another. I’d rather be able to locate stuff myself, than leave it to someone else. Reaction time and on going subscription costs are two reasons for diy

 

[outofthefire]

Falconers have used telemetry for years to find their birds, but other than the transmitter is obviously small I don't know much about them. I wonder how well you can pick up the signal from ground level.

 

[500e]

https://marshallradio.com/eu/european-falconry-products/european-falconry-dog-collars

Any radio signal can be disrupted VHF, UHF, LF, HF, there is nothing is perfect, a simple way to think is the higher the frequency the less cover you get & vice versa.
Repeaters do what they say repeat the incoming signal in real time.
Range extenders repeat with a delay on the same frequency (never seen one in the UK) you talk the extender records & re broadcasts on same frequency.
Unless you have a decent sized dog the commercial radio + GPS + battery + antenna
Range is improved by antenna height by a factor over more RF power notably on VHF\UHF
A poor radio with good Ae is usually better than a good radio with a poor aerial
There are a lot of amateur repeaters about the country