DMR VS TETRA

[welshevo]

ok guys... did a range test using 2 sepura SRH handhelds.... and got roughly about 4.2 miles in DMO at 2 watts... however recently did a range test using 2 x MD380 DMR handies... and can just about get 1 mile! on exactly the same route as the sepura test... so what i want to know is why??? tetra out performed the DMR no problems! but yet DMR struggles... ive even tried using external antennas on the MD380 and still poor performance.....

i need to increase the range of my DMR handies any suggestions??

any thoughts people of TM1?

[bigbloke]

Assuming that the comparison was made on exactly the same frequency, either:

Squelch set incorrectly on DMR sets (normal / tight)

TETRA set perhaps more sensitive receiver than DMR set (MD380s arent the hottest RXs and channel coding scheme on TETRA has better
error protection than DMR)

to increase the range of your DMRs, check your squelch settings, use better antennas and fully charged batteries :-)

regards

BB

[Admiral]

Just the obvious from me, make sure you have the power setting right, are you using the slightly bigger rubber duck that came with them, mine gets out okay as I hit my local repeater on high or low power 9 miles away from my couch with the stock antenna, obviously that's a repeater, so comparing oranges and apples to what you're doing.

1 mile is absolute pants, did you try them on analogue as well in case one of them is a bit poorly?

My second unit arrived yesterday, I will do some similar tests at the weekend as well as encryption testing.

[welshevo]

all good points raised here folks...the sepura handhelds were both using the stock antenna (stubby type) not helical... on 449.3750 (UO) band... and got great results in DMO.... the 1 MD380 was using a Stock stubby antenna whilst the other at a fixed point was connected using a Collinear white stick mounted outside high up... again on 449.3750 we tried both DMR PMR and UK simplex analogue and got the same poor results of a mile ....both batteries fully charged and both set to High output... the Squelch on the DMR handies were set to normal.... and by using the side button to open monitor... and still nothing.... so im a bit stumped....

[radiosification]

It's obviously not a fair test if one is on a white stick on the roof. Put them both on handheld antennas then the performance should be more comparable.

[paulears]

Yes, but the poorest performing radio was on a high up proper aerial, so should have had a huge advantage. Short aerial to short aerial should be substantially worse than one end having a decent aerial. Something is adrift here.

[radiosification]

Not necessarily. There might be something wrong with the external antenna so it could be messing up the test. That's the first thing I would try changing. Maybe the reflected power is very high, or maybe the cable is very lossy at this frequency. Or there could be a short in the cable and maybe it isn't even using the antenna.

Radio works in strange ways, so if you're doing a comparison you should always set it up as equally as possible. It could just be that the tetra radio was placed it exactly the right location to pick up a reflection, or there was a clear path to that point but not to the external antenna.

[tetramoo]

Hello Chaps

I had been experimenting with Tetra in Direct Mode Operation (DMO) for around the past 5 years now although subsequently 'sold up' my last bits of radio kit a while back due to financial constraints, having had the RoIP linking set up with a Simoco SRM1000 (410-430MHz) TZ band paired with a Sepura SRH3500 (400-433Mhz)TG band using the Signalink USB radio interface and the externally mounted collinear antenna was a Diamond X-50 2M/70M....Bored yet....!!!!
Got some great results in DMO using no more than 5W RF output power although factoring in coax loss and antenna dB gain from the X-50....for example 9 miles line of sight back to the X-50 from a less than 1W Motorola MTP850, also 10 miles (near line of sight) from a 5W SRM1000 to a 1/4 wave whip on my vehicle which was fitted with a 3W SRM1000 using 430MHz as the primary test frequency.
Having said this the best Tetra Handheld/Portable I have tried and tested for DMO range out of the Motorola MTH/MTP or Sepura SRP/SRH range was an old Motorola MTP700 with a 1/4 wave whip antenna attached which dates back to the old Gen.1.Tetra radio kit circa.Year 2000
Anyway that's my boring two penneth on the subject of Tetra DMO range and coverage.

[zippy]

im enjoying my dmr set, id love to have a go with tetra but the kit is still so dam expensive, I will just wait for TYT to knoeck out a tetra set for £100.

[radiosification]

I will just wait for TYT to knoeck out a tetra set for £100.

Probably won't ever happen. TETRA users generally have a decent amount of money to spend on a decent level of kit. They wouldn't want radios that break as soon as people start using them in heavy rain or have spelling mistakes in the menus. I mean, when they've already spend thousands on infrastructure, a few hundred for a decent radio isn't really something they try to skimp on.
Hytera, a chinese company, make TETRA equipment, but they are not super cheap. They also make good quality DMR radios.

[zippy]

I will just wait for TYT to knoeck out a tetra set for £100.

Probably won't ever happen. TETRA users generally have a decent amount of money to spend on a decent level of kit. .

I don't understand that statement fella, your suggesting that tetra prices are artificially high because the market can afford it and it keeps out the rif-raf like me.
I have no great knowledge on tetra, but I don't see a tetra handset being any more complicated than a 3g cell phone, they cost about £50 on the second user market.
tetra just has this mystique surrounding it because the old bill use them at the moment, im pretty sure a Chinese factory could knock them out at £100 a pop and make a good profit.
at my entry level I wouldn't care if the thing had spelling mistakes and firmware glitches and wasn't mil standard, its frustrating to be shut out of the market on cost, and a cost that is not justified.

[Farty]

DMO is s****e. You'd do better sticking a megaphone down your trousers and farting in Morse. Neither system works particularly well when independent of some kind of network, but then if you wanted to speak to someone across a network you could just use a mobile phone.

[pete_uk]

Digital DMO works well depending on your set up.

I have a Hytera DMR and its a solid piece of kit

[Farty]

MTH800s and Sepuras, and in DMO they're not terribly clever. Compressed audio that make them relatively unpleasant on the ear, and compared back to back with analogue the signal starts to fail long before analogue degrades to unintelligible. If you know of any better Tetra handsets then be my guest.

[welshevo]

My Sepura SRH handies outperformed my DMR and analogue radios in DMO... this was my argument... and also puzzling as i thought DMO was rubbish until i carried out testing....but im guessing its all preference on the user really... i preferred the audio from the Sepura than my DMR and especially my analogue radios...