Problems with Simulcast

[jonwienke]

would you post a diagram or a pic of this "paint can" thing. I've seen it referenced more than once. Thanks.

It's a old wives' tale that is unlikely to actually help simulcast reception. It's a crude form of signal attenuation the in most cases will be either too much or too little atttenuation to actually improve simulcast reception. But there is one guy who is obsessed with it and rarely misses a chance to post about it when simulcast is mentioned.

A variable attenuator is far more likely to be helpful, or better yet, a directional antenna to isolate the signal from one tower.

 

[kayn1n32008]

"It is sad that we would have to perform antenna joo joo to compensate for crappy engineering."



Wouldn't call it crappy engineering. LSM is a modulation scheme that was released post hardware design in the current line of Whistler products... Uniden has addressed this issue now with the soon to be released SDS-100, and Whistler to follow suit by the end of the year...

LSM was around before the HP1 and the 4/536 line of scanners.


Sent from my iPhone using Tapatalk

 

[iMONITOR]

would you post a diagram or a pic of this "paint can" thing. I've seen it referenced more than once. Thanks.

Ray

Although I don't have one nor have I tried one so I'm not here to debate if it works or not. It's probably based on the similar 'Cantenna' for WiFi. It is directional and claims to offer some gain. There are numerous pictures at the link below that might give you some ideas:

Cantenna
https://www.google.com/search?q=can...06fbAhWjFzQIHYj7CrwQ_AUIDCgD&biw=1405&bih=934

When applying a similar design, the idea is more about blocking or attenuating offending signals on the same frequency from multiple antenna sites, while concentrating on one and making that one the strongest one out of the group. In theory it may help. It would cost little if anything to make one up to play with.

 

[jonwienke]

Although I don't have one nor have I tried one so I'm not here to debate if it works or not. It's probably based on the similar 'Cantenna' for WiFi. It is directional and claims to offer some gain.

The Cantenna works OK as a directional Wi-Fi antenna if the diameter of the can is about 1/2 wavelength, and the driver element is poked through the side of the can 1/4 wavelength from bottom of the can, and the can is several wavelengths long.

For VHF, you'd need something about the size of a metal 55-gallon drum to make a cantenna.

For UHF, the can needs to be about 13 inches in diameter

For 800MHz, the can needs to be about 7 inches in diameter. But a paint can isn't going to work well even there, because the can needs to be several wavelengths long.

Just poking a hole in the side of a paint can and sticking the antenna inside won't do anything useful. The best you can hope for is that your particular simulcast situation can be helped by attenuating the signal, and sticking your antenna in the can happens to attenuate the signal just the right amount.

 

[rdelao_16]

Follow up

Good evening everyone.

I was going through my old posts and found this post. I thought I would give a little bit of an update from where I started to where I am now.

When I bought my Scanner, I was living in college on campus and the public safety tower I was trying to use was actually on the top of the hill on campus at my dorms. So I was actually right next to the repeater.

My theory is that the radio was having troubles getting traffic because of how close to the tower I was. Once I moved further away, I never had anymore problems. Now I'm roughly 10 miles from the tower and it comes in clear as a whistle with no issues. Maybe this is just a crazy thought but it's what I've come up with.

 

[dancrosoft]

Good evening everyone.

I was going through my old posts and found this post. I thought I would give a little bit of an update from where I started to where I am now.

When I bought my Scanner, I was living in college on campus and the public safety tower I was trying to use was actually on the top of the hill on campus at my dorms. So I was actually right next to the repeater.

My theory is that the radio was having troubles getting traffic because of how close to the tower I was. Once I moved further away, I never had anymore problems. Now I'm roughly 10 miles from the tower and it comes in clear as a whistle with no issues. Maybe this is just a crazy thought but it's what I've come up with.

Naa. This radio is literally incapable of reliably monitoring P25 Simulcast systems. On some of the reputable sites that sell scanners, they have even taken P25 Sim off the features list. Bottom line is that there is no reason why my TRX1 can sit right next to my Unication G5 and pick up nothing when the G5 is crystal clear. I have accepted it is what it is. I love my G5 and use it every day. I will probably purchase the new Uniden eventually but the G5 does it for me at the moment.

 

[BrianG61UK]

It's a old wives' tale that is unlikely to actually help simulcast reception. It's a crude form of signal attenuation the in most cases will be either too much or too little atttenuation to actually improve simulcast reception. But there is one guy who is obsessed with it and rarely misses a chance to post about it when simulcast is mentioned.

A variable attenuator is far more likely to be helpful, or better yet, a directional antenna to isolate the signal from one tower.

The description earlier in this thread sounded a bit like a cantenna.

But a cantenna that works at even the highest scanner frequencies like 800MHz would need a big can.

And would need to be aimed correctly at one of the towers.