Improving simulcast reception?

[N8SHA]

Since "getting back into the hobby" a couple of years ago, I've been pretty disappointed in the reception I get from the simulcast system which I primarily listen to. (I miss the VHF days...) Here's the rundown:

• Uniden SDS200 (and a couple of other scanners too)
• Diamond D3000N discone, mounted outdoors, about 15 feet off ground (pole on corner of house)
• Feed is about 50 ft of LMR400 with N connectors, Polyphaser 125mHz-1gHz surge suppressor
• Stridsberg MCS2004M 25 MHz to 1 GHz multicoupler
• Genesee County, Michigan, MPSCS Simulcast

Almost everything I receive on simulcast is pretty choppy, RSSI never better than about -120 to -112dBm.

I've been mulling over the idea of adding 800mHz Yagi into the system, pointed to closest tower. This and the discone would feed into a passive multicoupler / combiner from Stidsberg, and then into the other multicoupler. I understand the multicouplers will introduce a certain amount of loss, but I'm hoping the Yagi gain might offset it.

So, I am over thinking things here? Other ideas I should consider before soaking more money into all of this?

-Matt

 

[buddrousa]

-120 DB is a VERY WEAK Signal
-60 DB is a VERY STRONG Signal

 

[wtp]

could you just try the stock antenna and get back to us ?
with more antenna comes more signalS
at at time when you want less.
the problem with simulcast is too many signals.
with analog and simulcast you might hear a small echo and your head can still make it out.
with digital the computer 'sees' too many ones and zeros.
110110110 becomes 1l1l0o1l1l0o1l1l0o or more if you can now receive more towers.
and the computer shuts up.
also the signal stuff can be the signals cancelling out each other.
my county has gone from an 800 simulcast analog system to 700 simulcast digital and i have to stick my radio in the corner of a metal framed window and on a cell phone holder holding it horizontal.
it is like the rabbitear antenna dance of years ago.

 

[Ubbe]

Almost everything I receive on simulcast is pretty choppy, RSSI never better than about -120 to -112dBm.I've been mulling over the idea of adding 800mHz Yagi into the system, pointed to closest tower. This and the discone would feed into a passive multicoupler / combiner from Stidsberg,

I can't see Stridsberg having a suitable diplexer that would give you a lossless combination of the antennas and they will interact with each other. Your discone will have 10-20dB loss at 800MHz due to unwanted directivity of the antenna up in the sky. A yagi are a good way to solve that problem. There are reviews of yagis in the forum and some antennas are crap and some others are good and affordable. You should use a diplexer that pass everything above 600MHz from the yagi and below 600MHz from the discone and with a loss of less than 1dB.

If you can't find a suitable diplexer then you can get a $35 lowpass filter from Minicircuits to use in the coax from the discone and then connect the yagi and discone together with a T-connector. The yagi wont interrfere much with the frequencies from the discone but the optimum would be to use a highpass filter for the yagi to stop it from attenuating VHF/UHF signals. Minicircuit only seem to have a N or SMA connector types for that.

Lowpass filter
Highpass filter
Highpass filter SMA

/Ubbe

 

[N8SHA]

Unfortunately, it would be sort of tough (though not impossible). It's rack mounted and needs to stay there for regular use. I could take out to test, but even if it worked better, it would be sort of moot. Sometimes my listening room seems like a bit of a Faraday cage. Reception inside just isn't great with anything.

-Matt

could you just try the stock antenna and get back to us ?
with more antenna comes more signalS
at at time when you want less.
the problem with simulcast is too many signals.
with analog and simulcast you might hear a small echo and your head can still make it out.
with digital the computer 'sees' too many ones and zeros.
110110110 becomes 1l1l0o1l1l0o1l1l0o or more if you can now receive more towers.
and the computer shuts up.
also the signal stuff can be the signals cancelling out each other.
my county has gone from an 800 simulcast analog system to 700 simulcast digital and i have to stick my radio in the corner of a metal framed window and on a cell phone holder holding it horizontal.
it is like the rabbitear antenna dance of years ago.

 

[N8SHA]

Thanks for the info. Taking a closer look at the Stridsberg passive multi-coupler, I see it has more loss than I was anticipating. I'm glad I didn't jump the gun there.

I haven't been able to find a diplexer yet with any appropriate frequency ranges. I think giving the Minicircuit filters might be worth a try.

Thanks,
Matt

I can't see Stridsberg having a suitable diplexer that would give you a lossless combination of the antennas and they will interact with each other. Your discone will have 10-20dB loss at 800MHz due to unwanted directivity of the antenna up in the sky. A yagi are a good way to solve that problem. There are reviews of yagis in the forum and some antennas are crap and some others are good and affordable. You should use a diplexer that pass everything above 600MHz from the yagi and below 600MHz from the discone and with a loss of less than 1dB.

If you can't find a suitable diplexer then you can get a $35 lowpass filter from Minicircuits to use in the coax from the discone and then connect the yagi and discone together with a T-connector. The yagi wont interrfere much with the frequencies from the discone but the optimum would be to use a highpass filter for the yagi to stop it from attenuating VHF/UHF signals. Minicircuit only seem to have a N or SMA connector types for that.

Lowpass filter
Highpass filter
Highpass filter SMA

/Ubbe

 

[chief21]

So, I am over thinking things here?

You may wish to re-think your plans. Very often, the problem with simulcast reception is too MUCH signal... not too little. One of the simulcast systems I monitor (using an SDS200) necessitates using an unfolded paper clip as an antenna in order to receive a readable signal. If I change to the standard whip, or an exterior antenna, the signal virtually disappears.

Hard to believe, but it's true.

 

[krokus]

Do you have any LTE sites nearby, that might be causing desense issues?

 

[iMONITOR]

The Diamond D3000N discone is probably exacerbating the problem with MPSCS. It's likely overwhelming the SDS200 with everything except what you want to hear. MPSCS normally has great coverage throughout the state and you should do find with the stock back-of-set antenna that came with the scanner, or some other minimal antenna outside.

 

[maus92]

The OP's SDS200 should be able to deal with any simulcast distortion, but his 120-112 dBm RSSI is at best marginal. The yagi type antenna aimed at the most isolated site (from the yagi's point of view) of the simulcast cell is a good solution.

 

[espnty]

So having the same issue with the WS1065 getting to much signal /Would a Paper clip work?

 

[iMONITOR]

So having the same issue with the WS1065 getting to much signal /Would a Paper clip work?

Won't hurt to try, or any other minimal antenna. Just be sure not to damage the center connector on the BNC jack.

 

[Colin9690]

Like others have mentioned, I've had success with aiming a Yagi literally in the direction of the nearest site tower.