Dallas Fire Dispatch bleeding into Dallas Police Channels

TexTAC

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For the past several weeks I have been receiving Dallas Fire Dispatch (460.575) on some of the Dallas Police Frequencies (SE Patrol 460.5, CID/Gangs 460.475 and a few others) using a SDS100. It happens when both channels are active at the same time - I can hear both channels. It doesn’t help to avoid Fire Dispatch or use ATT or IFX on Fire Dispatch. Anyone else run across this before? Any suggestions? I’ve been scanning for years and this has never happened before.
 

jason51

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You just be near downtown Dallas? That is just due to the SDS scanner. It gets overloaded in high RF environments. Happens to me all the time, I have to use another model scanner when in the city if dallas due to that.
 

hiegtx

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For the past several weeks I have been receiving Dallas Fire Dispatch (460.575) on some of the Dallas Police Frequencies (SE Patrol 460.5, CID/Gangs 460.475 and a few others) using a SDS100. It happens when both channels are active at the same time - I can hear both channels. It doesn’t help to avoid Fire Dispatch or use ATT or IFX on Fire Dispatch. Anyone else run across this before? Any suggestions? I’ve been scanning for years and this has never happened before.
I have not seen that behavior on either of my SDS scanners, nor other models.

If, as Jason's noted, it's due to proximity, try tweaking the filters on the Dallas PD channels. If you use ATT or IFX, that should be tried on the DPD channels, not fire dispatch.
 

TexTAC

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I played around with the filters with only limited success. Dallas Fire Dispatch still occasionally bleeds into Dallas PD. I’m thinking it may be because I moved my antenna a little higher and closer to a wall with some light switches? Gonna play around with the antenna location (put it back where it was) and see if it improves.
 

hiegtx

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I played around with the filters with only limited success. Dallas Fire Dispatch still occasionally bleeds into Dallas PD. I’m thinking it may be because I moved my antenna a little higher and closer to a wall with some light switches? Gonna play around with the antenna location (put it back where it was) and see if it improves.
Seeing this issue at home (Plano?) or at work? (location if work?) While Dallas does have a transmitter site on Frankford Rd, the only DPD frequency licensed for that location is 460.175, North Central Patrol (Ch.6).

For Dallas Fire, 460.575 is not licensed near Plano.

If you are getting this at home, then some sort of interference is hammering you. Try each of the filters on your Dallas PD department channels. Also try IFX in the frequencies that get this issue.
 

TexTAC

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Yes, This is happening at home in Plano. DPD Channel 6 North Central Patrol comes in loud and clear. Much better then the other DPD channels. I elevated my antenna a bit more (about 6’) which helped clear up the other channels but I think that was about the same time this interference started to happen. (My antenna is a Larson triband NMO mounted to a 2’x2’ galvanized steel plate ground plane. Not the best for home use, but better than the upgraded rubber duck. Plus I can move it around wherever I want.)
 

hiegtx

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Yes, This is happening at home in Plano. DPD Channel 6 North Central Patrol comes in loud and clear. Much better then the other DPD channels. I elevated my antenna a bit more (about 6’) which helped clear up the other channels but I think that was about the same time this interference started to happen. (My antenna is a Larson triband NMO mounted to a 2’x2’ galvanized steel plate ground plane. Not the best for home use, but better than the upgraded rubber duck. Plus I can move it around wherever I want.)
My guess is that your getting some sort of intermod, where various frequencies combine and create interference on a totally different frequency. You'll see the occasional post where NOAA weather-radio drops in to visit some frequency well out of it's range.

You might try "Auto" for the filter setting, see if hat clears it up. Normally, you would not want to use Auto, since it really slows down scanning. But if "auto" eliminates the issue, then you know that one of the filter settings available cured it. And, again, try IFX on the DPD channels that are getting drive by interference from the fire frequency.
 

TexTAC

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I am 90% sure the issue I was having was caused by the antenna location. I moved the antenna back to where it was and the issue (knock on wood) hasn’t returned. I had moved it near an internal wall that had multiple light switches (including a dimmer on/off switch) and the master intercom panel for the house.

Now the only minor reception issues I have are (1) some of the Dallas PD channels are not as clean as I would like (improves some when I elevate antenna even just 5-6 feet) and (2) I am on the fringe of many of the Fort Worth system control channels (attic antenna may improve both issues). Thinking about the omnix antenna for the attic.
 

TexTAC

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Quick update ... The issue was resolved by moving the antenna. Also, I bought some RG8x cable and moved the antenna (Larson NMO 150/450/800 on 2’x2’ steel ground plane) to 2nd floor and what a huge difference. I put the antenna as high as possible in a corner facing Dallas and Fort Worth. Every channel I was receiving earlier is much stronger and clearer. Plus I am receiving more channels than before. I am getting control channels from 4 or 5 Fort Worth sites now and it was hit/miss before. Several aviation channels from DFW, Love, Addison, and even Alliance are now coming in with minimal static. When I use close call mode, I am getting readings from bands 1,2,3,4 and 6 when I used to just get 1, 3 and 6. I have my county and 8 surrounding counties programmed and have received signals from each county from home. People aren’t joking when they recommend putting an antenna as high as possible.
 

IAmSixNine

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Height and high quality low loss cable make a huge difference. Congratulations on the new antenna set up and the benefits of doing it right.
 
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