FRS vs GMRS vs 900 mhz radios ( performance)

[johnls7424]

Yeah for a business banded radio that is solely digital the price is definitely worth it. Clearity is superb compared to analog radios and like you and others stated its clear communications until your out of range. The DTR's tell you when your out of range. Which is nice. I also think 900mhz has a bit better penetrating power than UHF.

 

[johnls7424]

Anybody else want to discuss their successes or failures with 900mhz frequencies? Particularly the Motorola DTR series??

 

[poltergeisty]

I'm interested in DTR. Do you need software to program a DTR radio? They use FHSS, but how does one radio RX another? Is the PN code the same on all radios?

 

[michy]

Unlike most other CPS software, the DTR Radio CPS software is free and downloadable from Motorola.

Link:

http://www.motorolasolutions.com/we...ns/_Documents/_staticfiles/DTR_CPS_R03.01.zip


For the ones I have, I added each radio to each other radio (they are referred to as a contact).

Once they are added, they can RX each other.

I then put them all in a private group.

btw.. I have four, and once I had one configured, I just wrote the same configuration to all radios.

 

[poltergeisty]

Thanks for that! I did find the programing cable on eBay too!

So it's my understanding that no two DTR radios can hear one another unless they are in a "contact?"

I'm interested in what type of PN code the radio uses. Is it random so that you can't use your radio to hear another? I'm wondering about this because I know cordless phones that uses FHSS all have the same PN code.

Now I'm wondering if FHSS use a PN code. :lol: http://en.wikipedia.org/wiki/PN_code

 

[poltergeisty]

I found this interesting. This guy was able to follow the frequency hops with a Optoelectronics Xplorer

https://www.youtube.com/watch?v=lp4aZk3xscA

 

[johnls7424]

Yeah thats the VSLEP digital which even if you can follow the hops you will never be able to hear the audio.

 

[prcguy]

In theory no, NFM goes further than WFM due to less noise allowed into the receiver by the narrower IF filter in the NFM radio. Cut the IF BW in half like going from 10KHz to 5KHz and you improve the link by 3dB. If you are using a WFM receiver to pick up NFM signals then it will seem to be worse going to NFM.

In practice there is hardly any difference with a properly designed NFM radio and a WFM radio. Now make a bigger step like operating CW with a 2.5KHz SSB filter then switch to a 250Hz filter and you can improve things by about 10dB.
prcguy

I forgot to mention if you try MURS use one of the two wide band freqs in wide band mode. WFM goes further at the same wattage than NFM.

 

[N4KVE]

Many radio techs who work for entities are claiming less range since going narrow band.

 

[poltergeisty]

I have a couple Kenwood TK-373G radios and have never seen a difference with modulation. Been awhile since I programed them but I think there is NFM and WFM selection in the software. Something like that I could be wrong. It could very well be FM and NFM.

 

[Project25_MASTR]

I know plenty of systems that don't perform near as well since narrowband. Even on my equipment which has narrowband priority on it. Comparing a 25 kHz FM signal and a 12.5 kHz FM signal to a 3 kHz AM based CW or ssb signal is nothing alike unfortunately.

Sent from my ME173X using Tapatalk

 

[johnls7424]

They claim narrowband will only affect the voice transmission, making it not as loud. However like others stated I too believe the range is not as far with narrowbanding. Now this switch to digital does make up the difference to some degree. Lets it be note ( about 1 watt digital equal 4 UHF analog watts). So distance can be made up with a more powerful digital radio due to narrowbanding plus voice is alot better.

 

[johnls7424]

Not to bring back this post but I do have one question: What is the frequency range for the Motorola DTR radios? I know its in the 900mhz frequency range, but I wanted to know if theres an exact range that it follows?

 

[michy]

Not to bring back this post but I do have one question: What is the frequency range for the Motorola DTR radios? I know its in the 900mhz frequency range, but I wanted to know if theres an exact range that it follows?

The ISM band operates from 902 – 928 MHz, so my guess would be that range.

 

[johnls7424]

Thank you. These radios I might add are quite secure. Maybe not AES or DES encryption secure but pretty close.

 

[Hans13]

Question for johnls7424

Since it's been a while... How have the Blackbox VHF radios been performing for you?

 

[johnls7424]

I purchased the Blackbox VHF radios about a year ago or so. I cannot complain about them. The audio quality on them is what you would expect from a 180 dollar radio. Its not going to compare to a Motorola radio of a similar series. The battery life on the radio is only about average. I needed the radio for work on a local farm. Purchased 2 of them. When and if I am going to invest in UHF style radios I think I will spend a little bit more money and get DMR such as the Motorola XPR 6500 MotoTrbo radios. With the sudden push to digital and all becoming ever so more popular day in and day out I might bend over and spend 400+ per radio..

Still all in all its worth the cheap price for the blackbox's cause they already have paid for themselves and then some. Remember if your going to purchase them you will need the programming USB cable. The software is free from blackbox. You just need to download it.

 

[Hans13]

Thanks for the update. It's been very helpful and so has this thread.

 

[johnls7424]

Anytime.

 

[scannermanner1]

The ISM band operates from 902 – 928 MHz, so my guess would be that range.

Is there any way the dtr 650 radios can be programmed for 900 MHz digital conventional or maybe Analog ?