Spectra Installation- What Should I Expect ?

[jcork]

I work in an IT capacity and am installing digital video recorders in 2005 Crown Vics. The CV's have 16ch 100w Spectra's (circa 1990) and 100w amps in the trunk, at 154Mz. I am running into noise problems and would like some opinions on what 'good' looks like.

The radios have been 'ok' for 10+ years, BUT there are spots in town where they break squelch unless it is set at 10-12. With the new DVR's, they need to be squelched to at least 13 to remain quiet (and we are missing scan traffic). Is this 'normal' for a radio of this type? Or should I be looking at the radio installation instead of the DVR?

What is the reasonable lifespan of these radios in 24x7 service? Is there a specific failure that normally makes the 'trash it' determination? I see they commonly sell for $200-300 used.

If we were to get *new* equivalent Motorola analog systems, would they have more selective front ends and be more resistant to the CPU generated noise?

I am looking for suggestions on solving this RFI issue.

[n1pfc]

I work in an IT capacity and am installing digital video recorders in 2005 Crown Vics. The CV's have 16ch 100w Spectra's (circa 1990) and 100w amps in the trunk, at 154Mz. I am running into noise problems and would like some opinions on what 'good' looks like.

I've run into this before with video recorders.

The radios have been 'ok' for 10+ years, BUT there are spots in town where they break squelch unless it is set at 10-12. With the new DVR's, they need to be squelched to at least 13 to remain quiet (and we are missing scan traffic). Is this 'normal' for a radio of this type? Or should I be looking at the radio installation instead of the DVR?

I'd look at the DVR's since it's the only thing that has changed in the car

What is the reasonable lifespan of these radios in 24x7 service? Is there a specific failure that normally makes the 'trash it' determination? I see they commonly sell for $200-300 used.

If we were to get *new* equivalent Motorola analog systems, would they have more selective front ends and be more resistant to the CPU generated noise?

I am looking for suggestions on solving this RFI issue.

I'd say you're probably going to have the same issue with a new radio as with an old one in this case. Odds are the RF the DVR is spewing out is close to the frequency that the radios operate on. Spectras were a high end motorola product. Even if you went with the top of the line XTL5000's you may run into the same problem. Typically electronic equipment will spew fairly wide band noise so it may be difficult to isolate the exact frequency of it.

If the agency you're installing these for have portables, try sweeping them around the various cables that come out of the DVR and the DVR itself, it should have a similar effect with the portable as it does with the mobile radio. This should allow you to isolate exactly where the noise is coming from (the DVR box itself or the wiring associated with it)

Is the DVR In a plastic or metal case? if it's plastic, put a metal box around it, although it should meet FCC spec already. You're most likely culprit is going to be the wiring coming off the DVR (control cables, video cables, and power). Try snapping some ferrite beads around these wires and see if the interference is reduced from the DVR. You can also try wrapping the wiring around multiple times. You're proably also going to need one at each end of each wire unless you can bundle the wires together around one big ferrite bead.

Sounds to me like it's radiating along the wiring coming out of the DVR box and getting picked up by the spectras.


I've run into this before with video systems in police cruisers as well as with destination signs on busses.

Let me know how you make out.

Kurt

[jcork]

So, having the squelch level at 10-12 is not uncommon for a Spectra in a Crown Vic (ignoring the DVR issue) ?

[007]

So, having the squelch level at 10-12 is not uncommon for a Spectra in a Crown Vic (ignoring the DVR issue) ?

It is uncommon...the problem is likely not the radio.

The DVR is likely the cause, so grab a handfull of those snap-on ferrite beads and see if the noise goes away.

Normally, the Spectra or X9000 squelch could be between 5-8 depending on local conditions. Mine breaks squelch at 2-3, and I leave it at 6.

[jcork]

It is uncommon...the problem is likely not the radio.

Normally, the Spectra or X9000 squelch could be between 5-8 depending on local conditions. Mine breaks squelch at 2-3, and I leave it at 6.

WITHOUT the DVR, our squelch must be at 10-12 in normal use, and I was trying to figure out if that was within normal limits or if the radio installation was problematic to start with. Although this installation worked fine 15 years ago, I'm sure we have additional noise sources in the environment we didn't have back then.

I'm sure the DVR requires another 1-2 points on the squelch; I'm trying to figure out if troubleshooting the radio noise floor will pay more dividends than additional shielding tricks on the DVR.

I truly appreciate all the advice; I made Amateur Advanced in my youth so I know the lexicon, but spend my days now with computer network issues.

[SlimBob]

WITHOUT the DVR, our squelch must be at 10-12 in normal use, and I was trying to figure out if that was within normal limits or if the radio installation was problematic to start with. Although this installation worked fine 15 years ago, I'm sure we have additional noise sources in the environment we didn't have back then.

Most likely there are more noise sources now; it may be worth it to go ahead and start ferriting everything you can in the car to get the noise level down.

I'm sure the DVR requires another 1-2 points on the squelch; I'm trying to figure out if troubleshooting the radio noise floor will pay more dividends than additional shielding tricks on the DVR.

A little of both, but the DVR is contributing as well.

I truly appreciate all the advice; I made Amateur Advanced in my youth so I know the lexicon, but spend my days now with computer network issues.

That's rather fortunate, but a bit disarming -- you've both dated yourself and not dated yourself. But in a nutshell, you want to keep any device from radiating EMI if at all possible.

[K8COP]

What the brand name of the DVR's. Our agency is looking at new in car video systems.

Jim, K8COP

[jcork]

What the brand name of the DVR's. Our agency is looking at new in car video systems.

Jim, K8COP

These are Aegison 6010M 's. The nice thing about them is they have a streaming server that can archive the data automatically. There are plenty of systems that let you collect data, but once you have 200+Gb of data locked in a car, it's trouble to get it out.

[jcork]

That's rather fortunate, but a bit disarming -- you've both dated yourself and not dated yourself.

'Dated' covers it well! Most of my experience involved fixed base in the 70's at HF. Although I read up on RFI/EMI back then those books have long since gone away and I'd hope the technology has improved.

I'd be interested in any current reading you might suggest on the subject.

[n1pfc]

What the brand name of the DVR's. Our agency is looking at new in car video systems.

Jim, K8COP

These are Aegison 6010M 's. The nice thing about them is they have a streaming server that can archive the data automatically. There are plenty of systems that let you collect data, but once you have 200+Gb of data locked in a car, it's trouble to get it out.

Taking a look at how it interfaces to the control panel I would DEFINATELY put some ferrite beads on the control cable that runs between the two. It's RS-232 which could spew RF. The other cables to definately isolate are the power cable and the remote trigger wires. You're probably wiring the remote trigger wire to actuate the recorder when they hit the light bar if you're using it. (most I've seen are set up this way). If you're using any control signals to the camera for PTZ (Pan / Tilt / Zoom) I'd ferrite bead those as well.

Kurt

[K8COP]

Have you spoken to their tech support? Maybe you are not the only agency with the same problem. They may have a tech sheet on correcting it.

Jim, K8COP

[Jim202]

Another area you might be caught up in is if they have mobile computers in the car. Many of these send out trash that can just render a VHF radio receiver useless.

Tou might try shutting everything off in the car and pulling the power plugs. Test the radio with the dispatcher or another car. Then start turning on one device at a time. You should find something that will light up the receiver.

One other issue that may effect you is the car digital clock. If you just happen to luck out and have a frequency that falls on or near one of the birdies from the car clock, your screwed. getting to the power feed for the clock and or car radio may be a simple pull the fuse in the under dash fuse panel.

You could also be unlucky and have the car computer module spraying trash on or near your operating frequency. It might be worth seeing if there are any other channels in the radio that you can use to do some of your testing. This will give a hint of it being specific sikes or wideband noise causing your trouble.

The data cables from a laptop going to an external modem / radio link can play havic to a VHF radio in the car.

Your just going to have to do some leg work to find out the source of the noise.

One last thought that came to mind. If you have cable TV in your area where your having troubles, is it by any chance leakage from the cable TV system causing trouble? You did mention that you had trouble in spots around town. If the problem is from the cable TV, it is easy to prove. Take a scanner and listen to the voice channel frequency that uses 155.750. You should not be able to hear anything. If you hear the voice audio from the cable, then the leakage is higher than allowed and the cable company needs to fix it right now.

If you find the cable system is causing part of your problems, be gentle and try contacting them. Ask for the system engineer or somebody that has some technical pull in the company. Talking with the person that answers the trouble phone is like talking to a dry stone. They are dumb, don't know anything and are probably half way across the country. You might get further by making a visit to the local office. Just expect to get the run around. Again they are just clerks and don't have a clue what your talking about. Keep pressing for the contact name and number for the local engineer or service person responsible.

Jim

[jcork]

You're probably wiring the remote trigger wire to actuate the recorder when they hit the light bar if you're using it. (most I've seen are set up this way).

Kurt

Actually, what I'm trying to do with this installation is run the camera 24x7, no triggers, no user intervention. The interior of these cars is mess from a human factors standpoint and I'm trying not to add to that. I should have outlined my system design a bit up front.

When the power comes up, the system is online and recording 30fps. When the ignition power drops a 45 minute timer continues applying battery power to the DVR and such. I have a Wifi bridge pushing data out to an archive server off the same power (disabling the bridges shows them as blameless last I tried).

EDIT 7-20-05: Retested, and found the bridges to be the hottest source in the installation. Was originally using Dlink DWL-810's and now using 3Com 3CRW675075.

I am using a DC/DC converter for the DVR, wireless mic receiver, and wifi bridge; all shielded and grounded and mounted in the trunk while the camera is up front.

Later, I plan to add some switching to drop the recording while in the garage and drop the wifi while out of the garage; this causes some inefficiency in recording but I can control the data rate to compensate. In our department, cars are not issued to individuals and they spend some time parked in the garage where download takes place.

[jcork]

Another area you might be caught up in is if they have mobile computers in the car.

One other issue that may effect you is the car digital clock.

You could also be unlucky and have the car computer module spraying trash on or near your operating frequency.

If you have cable TV in your area where your having troubles ...

Jim

I will start running these down; thanx muchly. We don't currently have laptops in the car, but that's inevitable and I expect more adventures when they go online.

The spots where we have the most noise, are near banks, and in the very middle of downtown, which is geographically lower than the rest of town. There are no serious EMI emitters that I can readily identify, but that just means I'm not looking in the right direction so far.

I have checked with the DVR manufacturer's tech support, with limited success (which doesn't surprise me- their stuff works fine, and they can't solve everyone else's problems).

Do the Spectra's need any special power line filtering to avoid noise, or do they just happily plug into whatever 12v supply a vehicle has? I guess I'm wondering if a DC/DC converter could be a possible help or just another noise source.

[wx4cbh]

Having installed hundreds of Spectras and Syntors in Crown Vics and other vehicles, I can say that Spectras and Syntors rarely need any form of power line attenuation when installed correctly. Attenuators are band-aids, you're not fixing the problem, you're just hacking the real problem. Regardless of how damn good somebody thinks their equipment is, if you have to put external attenuating devices on something, then the question becomes which unit is the real source of the problem? Hate to say it, but Kustom cameras and radars and Mobile-Blindness camera units are real sewer holes of noise. Fortunately, they RARELY bother the Spectras and Syntors.

Would the power source for the radio be that damned Ford-provided "noise" connection in the trunk on the right side behind the felt liner? If so, run the red main power wire and the green contrl head wire for the radio to the large connector at the fuse/relay box under the hood. If both the DVR and the radio are connected to the trunk power connection, you're taking your chances. Most of the radio/interference/voltage problems solved by our shop on law enforcement optioned Crown Vics is solved by NOT using the under dash or trunk connections for the radio power source. We have never failed to solve noise problems when we moved the radio main power and green wire connections to the underhood area as the first measure.

Where is the green wire of the orange and green pair at the control head end of the control cable connected to power? If it's not attached to the SAME voltage source point as the main (red) power lead, there's a potential problem. Where is the orange wire connected to power? Where is the radio grounded? The "amp" you mentioned is the radio itself. The control head is what's up front, and it does contain some RF susceptible components but usually there's already a component problem rearing it's ugly head when the control head gets involved.

You also need to determine that the noise is actually getting into the receiver through the antenna or if it's being induced on the radio's cables from some source within the car (not likely unless we go back to that green wire/orange wire thing). When the noise is present, is the noise present when the antenna is disconnected? Have you tried rerouting the antenna cable? Sometimes changing the length of the cable will eliminate noise. Have you tried rerouting the DVR cables? Has someone neatly coiled up excess antenna cable, creating a nice receiving coil? Are there any other wires or cables neatly coiled? If so, smack the neat freak's hands and simply pinch the coils together in the center so as to make a nice flat loop bundle instead of a coil. Just be sure not to crunch the ends of the RF cable's loops - you need to maintain about a 1 inch radius on those if they're RG/58, more if the cable's larger.

Does the noise occur at the same geographic locations? Banks, gas pumps, ATMs, fast food drive-thrus, point-of-sale cash registers and store computer systems, cable TV lines, etc are notorious noise sources.

Does the DVR have a wireless mic? Is its signal clean and on-frequency? Does the DVR receive the wireless mic's signal through a scanner mounted in the DVR's case? Scanners are notorious noise generators. If it has its own receiver as part of the electronics, what spurs might be generated by that? In addition, a common ground point for all the equipment in the trunk does a lot to eliminate noise.

There are more things to look for but the above are some of the more frequent problem sources. Most of the time it's a combination of factors that resolve these problems. Just remember, the remote cables for the DVR are nothing more than antennas for radiating noise generated by the internals of the DVR. We like ferrites for the spurious noise shielding inadequacies of most of the law enforcement equipment out there. Ask me sometime about certain strobe light units.

[jcork]

Having installed hundreds of Spectras and Syntors in Crown Vics and other vehicles ...

Thank you for your extensive list of problem areas. I'd say I now have several weeks of things to chase down. I never knew there were so many wrong ways to install a radio system.

As I make progress, I'll certainly post any updates here.

[wx4cbh]

Well, if there's anything I've learned in 35+ years of radio work, it's that when you're trying to do an equipment evaluation, it's absolutely necessary to do proper installations so as to eliminate as many unknowns as possible. Bad installations put you at an immediate disadvantage and skew the whole process.

Whether it's inexperience, a lack of knowledge, a lack of documentation provided to the installer, or just a "rather do it my way" kind of thing that causes the original problems, going back and doing things the way each manufacturer wants it done usually cures all but the worst cases, and most of those are curable by adding the bandaids.

Short story: had a camera once a few years back that would turn on and off and a radio that would change channels just by operating the power door locks on the car. To make a long story short, the problem wasn't a voltage spike or similar electrical glitch. The digital toggle signal the door lock assemblies used was identical to the digital signal that the radio and the camera used for their respective functions. By removing the radio and camera power sources from the police package wiring harness under the dash and making the connections to the large power connection at the fuse/relay box cured the problem. Trust me, we didn't make that seemingly smart move until much hair pulling had transpired.

[radioguruphil]

Try moving the antenna to the roof if it is on the trunk.

[Will]

There are some receiver noise problems that can show up in the older Spectra radios. I have been working on Spectras since they first 'hit the streets' in the late 80's. I also have done a lot of R & D to find out why these and other Spectra problems come up as the radios get older.


A spectrum analizer is needed to "sniff out' the RF in the car and it's other installed componets. Also the noise floor in your city probally has risin a lot in the past 5 to 10 years with all the 'junk' out there generating RF in the VHF band. I remember simmular problems and looking at the Hi IF with the spectrum analizer to find the interference or desense on receive.

[jcork]

I bought a portable scanner and did some testing. I don't find any Cable TV leakage in our problem areas of town, but I do get some occasional blasts from a paging service.

I ferrited everything I installed at each end of the each wire for some benefit.

I went over the installation with an HT-1000 portable (squelch set internally) and it never broke squelch.

I set the squelch at threshold on my portable scanner set for the band in question and it identified the Wifi Bridge as a hotspot. The Ethernet leading to it was only a mild radiator. As a frame of reference, I can't get this scanner to unlock within 5' of a computer, and in the trunk I had it break squelch when I got the antenna within an inch of the bridge.

The wireless mic receiver is switch-selected for frequency at 900Mz and was not a factor.

My next step is to try and find a spot in the trunk (tail light?) where I can let the Wifi Bridge radiate out the back and put a reflector behind it to try and keep the trunk as clean as possible. The other solution is complete shielding and an external antenna. This device only needs to move traffic about 20' clear line of sight at 5Gz.

[SlimBob]

The wireless mic receiver is switch-selected for frequency at 900Mz and was not a factor.

I look forward to a future "worked all squad cars" award for 33cm in your area. Well, you'll probably beat me to "worked all cordless phones" first.