Non-trunk simulcast

[comspec]

When discussing the SDS100, the biggest improvement that I hear being discussed is the I/Q tuning and how it improves reception of digital simulcast systems. Almost always, the systems discussed are Phase II trunk systems. Where I live there is a simulcast single frequency non trunked system. The system used to be analog, but they recently went P25 and what I notice is that there are large areas where I hear absolutely nothing on My BCD scanner where I previously had loud and clear reception. There are also areas where it comes in well. So it got me to thinking, could this be a simulcast issue? Even though it is only a single frequency conventional system, the same problems with decoding digital are possible. If this had been discussed before I apologize, but wondering, does the SDS100 help with such single frequency simulcast systems too? Most of the posts I have read seem to concentrate on the P25 Phase II. I guess the combination of TDM and simulcast seems to be the issue. I don't even see much discussion on Phase I P25 trunked systems. So perhaps there is no improvement on other systems.
So far I have seen the upgrade to the SDS100 as unnecessary as the only P25 Phase II trunked system near me seems to come in loud and clear and as far as I can tell, I am not missing many transmissions and can easily follow conversations. This new single frequency system on the other hand seems to be giving me a lot of trouble. Wondering if the upgrade to the SDS100 will improve my experience, but reluctant to plop down that kind of money just to have the same reception. I know no one can answer for sure, but though I would solicit feedback from other people's experiences.

Thanks.

 

[R8000]

Wondering if the upgrade to the SDS100 will improve my experience

Yes

 

[werinshades]

I would investigate further to find out if they encrypted their new system. Local forum might be a place to ask.

 

[comspec]

I would investigate further to find out if they encrypted their new system. Local forum might be a place to ask.

Thanks for the suggestion as that was my first thought, but It is not encrypted. I used to receive it crystal clear in my house no issues. Now all of a sudden, I can barely hear it at all and sometime only catch every other word, which I wouldn't be able to do if it were encrypted. When I take it on the road, I usually hear nothing but then all of a sudden in some spots it comes in clear.

To be honest, my BCD436 is acting up and I am probably going to buy an SDS100 anyway. I am just skeptical that it will solve the problem. Given that almost all of the posts about LSM are with respect to 700Mhz trunked systems, I am just not convinced that the SDS is going to help on this oddball.

 

[ofd8001]

This sure does sound like simulcast distortion.

I had a big problem with simulcast distortion which was greatly improved, but not totally, absolutely, simulcast issues. It is like day and night. If I had to replace a scanner, it would be with an SDS model.

Lastly, for what its worth, on simulcast distortion, it doesn't matter whether it is a trunked or conventional system. It is a matter of multiple transmitters and their signals hitting your scanner at just about the same time.

 

[tvengr]

So it got me to thinking, could this be a simulcast issue?

If you let us know the frequency, agency, and location, we can look it up to verify if it is simulcast.

 

[chief21]

Lastly, for what its worth, on simulcast distortion, it doesn't matter whether it is a trunked or conventional system. It is a matter of multiple transmitters and their signals hitting your scanner at just about the same time.

^^^ Yep... what he said ^^^

 

[toad99]

The SDS scanners work equally well for both Phase I and Phase II simulcast systems. As long as the signal is digital.
No improvement on any analog simulcast signals.

 

[comspec]

Thanks everyone for their opinion. Well, I decided to answer my own question and I needed an excuse to purchase an SDS100 so I did the deed. The answer is? Better, but still really not working as well as I had hoped.

I tested it by parking my BCS436 on that channel to try to hear if I heard anything. Usually I would hear static, some R2D2 noises and the occasional word here and there. On the SDS100 I heard nothing, not even static. Thinking that perhaps I was missing it because the radio was scanning I parked the SDS on that channel as well and bingo, started to hear transmissions. Started to play with filters, and other settings to see if it made a difference. None of them made a difference as far as getting it to pickup anything while scanning. Listening to that frequency only, Normal filter seemed to give the best results, but only when stopped on the channel, not while scanning. Nothing is heard when scanning.

Now what I noticed is regardless of what filter settings I use, the RSSI fluctuates very rapidly between about -94 and -107. I don't see this rapid fluctuations on other channels. The RSSI is constantly changing. When it gets down to about -104 the signal does sound a little distorted but I can make out what is being said.

I admit I am surprised I am still having trouble. When the system first went digital I picked it up loud and clear, no issues. In the last 2 months or so it has been impossible to pick up on my BCD436 and a challenge with the SDS100. However, the SDS100 can pick it up. So clearly the SDS is helping even if it doesn't completely solve the issue. I am only about 1 mile from one of the transmitter sites and about 13 miles to the next closest site. When this was analog, I was able to pick it up even without an antenna on the radio.

 

[tvengr]

Try using IFX on the frequencies giving you trouble. You could be getting interference from a nearby broadcast station or cellphone tower.

 

[werinshades]

Try using IFX on the frequencies giving you trouble. You could be getting interference from a nearby broadcast station or cellphone tower.

..or the Attenuator on the site(s).

 

[comspec]

Thanks for the suggestion about the IFX I forgot about that one. It seemed to increase the RSSI and now it hovers around -87 or so up from -104 to -94. But again, when I am scanning it doesn't seem to stop on that frequency only when holding on that channel. So now that I turned on the IFX, I will try all over again with the filters and attenuator.

I guess the message to any other prospective owners is that the SDS isn't a magic box and won't make all your problems go away, but at least for me I am hearing something again whereas with the BCD I heard nothing. Definitely a step in the right direction. For all the other systems that never game me any issues, including conventional analog, I am noticing no improvement, but no serious degradation either. The SDS100 and BCD seem to perform equally well and I don't see anywhere where the BCD performed better, except perhaps scanning speed.

As much as I am having "fun" with the new scanner, I have to mention that I have a Radio Shack PRO-2006 base scanner that has been running flawlessly for over 25 years and for conventional analog it beats any other scanner I have owned even just using the back of the set antenna. I don't think we will ever get a scanner that performs as well on digital as the PRO-2006 did on analog. At least not one I can afford.

 

[werinshades]

I guess the message to any other prospective owners is that the SDS isn't a magic box and won't make all your problems go away....

I'll agree on this, because the difference is this scanner's sensitivity could bring about a whole new set of problems with overload. One thing that Uniden provides is the "tools" to correct some if not all of these problems with filters, IFX, and for me attenuator usage. Some systems are problem free, then you might encounter a frequency that you're having issues with, similar to what you're experiencing. All we can do is make suggestions to you and others having issue, as we're not always sitting in your chair and hearing what you're hearing. The other issue I've seen here is patience, or lack thereof. While I agree a $650-700 scanner should work "out of the box", this is a entirely new technology that might require tinkering. I hope you can get this figured out over time. Filters, IFX, attenuator usage, modulation change seems to be the "magic" you speak of.

 

[tvengr]

Make sure that the service type for the frequency is enabled. Also, check to see if you accidentally locked out the frequency. You will not receive a locked out frequency in scan but you will be able to receive it when you hold on it.

 

[MTS2000des]

No has mentioned noise floor. Is this system on VHF, UHF or 700/800? VHF is a band full of "hash and trash" in many areas thanks to low rent electronics from China and if your receiver front end is bombarded with garbage, it doesn't matter if it's a Uniden scanner or an R-8600. Just because your raw RSSI is -94 to -107 (which is good) the magic bullet is what is the BER and what is your ambient noise floor?
It would benefit us to know WHAT the frequency is and associated license. The buildout of the system may also play a factor in receiver performance. When linear simulcast (CQPSK modulator) are built, there are distance limits between transmit sites and "designed in" nulls. Lots of factors can affect performance.

 

[tvengr]

Also, check to see if you accidentally locked out the frequency.

I should have said avoided in this case. Too many different scanners!