receivers with new 1258MHz option

[SecretSpy711]

Are you guys going to make custom Lawmate receivers with the 1258 option as well?

I previously owned the other brand and it crapped out on me, which is why I bought a Lawmate. My friend's receiver may also be starting to go bad.

Just to be clear, the receivers that are/went bad were NOT bought from RMRC.

[IBCrazy]

Lawmate is proprietary. RMRC has been working with some other manufacturers. Belive it or not, the "cheap digital" unit from RMRC got a revamp and is probably the best out there by now.

The digital had a sensitivity of ~-91- -98 db depending on the RX. Lawmate maskes -85db at best. The problem was signal filtration. RMRC figured out the problem and fixed it.

-Alex

[Hucker]

The digital had a sensitivity of ~-91- -98 db depending on the RX. Lawmate maskes -85db at best.
-Alex

Are you saying there is a 6 to 13 dB improvement just on RX side? Assuming noise floor is good, that will make for quite an improvement!

[IBCrazy]

Are you saying there is a 6 to 13 dB improvement just on RX side? Assuming noise floor is good, that will make for quite an improvement!

Yes. How do you think RMontiel gets the distance he does on such low gain?

-Alex

[Soldier53]

Hi, I just received the new ready made 1258/1280MHz RX set with the upgrade saw filter and a 400mw tx with a patch ant. what can I feel is a good range to get out of it? I'm all so looking to get a OSD to put in line, can some one give me some ideas? thank you all for the help! :-)

[1320Fastback]

Hi, I just received the new ready made 1258/1280MHz RX set with the upgrade saw filter and a 400mw tx with a patch ant. what can I feel is a good range to get out of it? I'm all so looking to get a OSD to put in line, can some one give me some ideas? thank you all for the help! :-)

I got the same stuff as you except also a V antenna.
Being new to all this I haven't pushed the limits yet (not even close) but have read that a 400Mw 1.3 system shoud go out 3-11 miles (6-11KM). Of course this ALL depends on LOTS of variables like your location, your setup (gear separation) and RF conditions.

Here's a good post with videos that show 26 different OSD's.
I am leaning to the RV osd or the Cyclops NOVA. Really like how they look, lots of useable info without all the clutter.
http://www.rcgroups.com/forums/showthread.php?t=1685356
Research though as they all have issues. Well most of them.
Please don't ban me for linking to RCG...., it's a helpful link for beginners like us

[Vitamin J]

Does that mod also fix the reliability problems? I had one of those cheapo ones and it seemed to work normally but then one day I turned it on and it could barely receive the signal when my plane was sitting right next to it.

[SecretSpy711]

VitaminJ that's what mine did. What I'm hearing is that a Lawmate with upgraded SAW filter would be the best quality AND reliability? Others say the Lawmates are better too.

I guess it would be harder to get an extra channel on the lawmates since they use discreet dip switches.

According to RXExplorer, upgrading the SAW filter gives about 3dBi, which is the equivalent of doubling your transmit power.

[IBCrazy]

Here's what you need to know about Lawmate: They copied the Comtech module and put a 21Mhz SAW filter in it. The filtration was improved, but not the sensitivity.

The Digital RX on the other hand had external noise problems. The manufacturer tried to fix the problem with a faraday cage. The problem was that the RX was so sensitive that the nearby radio transmitter for control often overrode the signal by exciting the cage. So what RMRC did was install a small device that cut the EFI noise from entering the module.

Mind you, this is sensitivity, NOT signal processing.

Signal processing is a totally different ball game. Signal processing is typically where Lawmate comes through. This has components both common to the module and common to the open board inside.

So basically it comes down to what your problem is and how you intend to tackle it. I personally use a Lawmate RX on my head-mounted ground station. I also use it on my 3 turn helical station. However, my long range system uses the digital VRX.

This is precisely why the question "which is better" is one of the worst questions you can ask.

-Alex

[Hucker]

I must admit I was scratching my head on RM's range, Sircana's antenna's couldn't make THAT much difference. That is good to know.

I'm going to show my ignorance here, when you talk about the rx sensitivity in dB is it apples to apples when comparing to 2G4? By that I mean, because of physics, lower frequency should have better range, does that get included in your 98db sensitivity or is that a separate effect? I'm guessing propagation efficiency isn't part of RX sensitivity but the boundaries of the parts in the RF link aren't always clear when you start putting numbers on them. If a 1G2 rx and a 2G4 rx have the same sensitivity (and tx power etc) then the 1.2 should do even better because lower frequency generally goes farther.