Posted: 7/31/2009 2:38:51 AM EDT
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Gents,
I am looking to put together a kit similar in design to the RACES go-boxes that I've seen on here. The purpose of this kit would be for use in dismounted LE tactical/surveillance situations, where a standard handheld police radio won't have the power to transmit clearly. I'm still toying with the idea in my head, and I'm not a 'radio' guy, so please bear with me. A bit of background on our county's radio system - It's a UHF system with a repeater on a mountaintop in the county. There are quite a few spots in the county where a handheld radio cannot transmit and hit the repeater - I assume this is a power issue? Although I've been down in some holes and gulleys and not been able to 'get out' either. Vehicle-mounted radios (I think mobile is the correct word) don't seem to have any problem hitting the repeater just about everywhere in the county. Handhelds do not run off a repeater in the car, they transmit directly to the mountaintop repeater. The system is not trunked or secure, so operational security would rely on code words mostly. Back-up comms or more sensitive conversations would be conducted on cell phones, although service is not available county-wide on some carriers (verizon, us cellular etc) Thus, I am trying to put together a lightweight, manportable UHF radio kit, which has the power of a vehicular mobile radio, while able to be transported by a single officer in a backpack conducting surveillance operations. I'm thinking something very similar to the SINCGARS or PRC-77 manpack systems in the military. I've already got a Motorola mobile radio, I believe it's a Maxtrac. It can easily accept the right channels and PL codes to access the net. I'm looking at building the kit in a Pelican case, no bigger than necessary to hold the radio itself and batteries. I'm hoping an antenna and handset can be run through grommeted holes in the box, so that the box can stay shut and left in a radio pocket of a rucksack or backpack and remain operational. What sorts of batteries, tape/whip antennas in the 3-4' or shorter range, and handsets are out there that I should be looking at? Primary considerations are durability in field conditions, cost, and ability to transmit 15-20 miles to the repeater. Like I said, this idea is still mostly in my head. Any recommendations would be greatly appreciated, and if I have not conveyed my idea well enough please ask any questions and I'll try to explain. |
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Quoted:
I would look at getting car radios that can cross-band repeat... HT to Car, Car to tower... then you no longer have to carry around big radios and batteries on dismounted patrols. Great idea, but not gonna happen. This is a project I'm putting together out of my own funds, for my own uses while conducting surveillance. No way can I begin to justify funds on that kind of scale (hell, even on a small scale) for an activity which occurs with infrequency. I'm not even out of the planning phase, and I may determine that the costs would greatly outweigh the benefits, especially in this age of cell phones. But since I already own the most expensive part (the radio) I figured I'd kick around the idea... |
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You might look at somthing like this for the batteries.
2 x 12AH Sealed lead acid This seems to be the recommended way to charge them. Battery Tender Jr |
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Couple of things.
One, when you're doing surveillance in one of these locations, do you necessarily need to get out to the repeater system? Perhaps just using a simplex frequency (aka "talkaround") in the immediate area would suffice. Second, a large portion of the improved performance of the vehicle mounted radios is probably the difference in antenna performance, not just the power output of the radio. It's entirely possible that a handheld radio used with a high performance antenna would make a much more efficient portable package than a mobile radio in a case with a big gel cell battery. |
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Handheld antennas are notoriously inefficient. Can you try a better antenna? How about a UHF 1/4 wave groundplane? Should be compact.
Would a little UHF yagi work with your handheld to get "out" of the holes? You know where the only repeater is, so direction is easy. Hopefully you could still carry the handheld and forego the weight of mobile rig + batteries. That said, check into the nano phosphate batteries. They keep 80-90% of the voltage until they near end of discharge. They charge quickly, too. Not cheapy, but a neat alternative to the regular sealed lead acid battery. Lightweight from what I understand. Not sure if they have the power level you want, but worth a look. |
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I'd definitely try the handheld + portable yagi route.
get a little folding tripod for the yagi so you can use it hands free. Carry a little compass so you know where to aim the yagi. cheaper, way lighter, and easier than humping a man-pack mobile radio with just an omni vertical antenna. |
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Quoted:
Any recommendations would be greatly appreciated some ideas for you: http://www.iportableus.com/ see also tke multiple links in http://www.ar15.com/forums/topic.html?b=10&f=22&t=604477#10323272 and the battery capacity info here http://www.ar15.com/forums/topic.html?b=10&f=22&t=604477#10323268 ps: one thing –– why is this strictly on your nickel, and not the department's? ar-jedi |
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Quoted:
Wouldn't a tripod and yagi attract a little attention during surveillance work? Probably about the same as a manpack radio lol. Maybe a few more specifics about how your operations would allow us to offer more informed advice. Is this people on foot or vehicles... what kind of terrain... what kind of possibilities are there for concealing equipment. Another possibility would be a portable repeater as a sort of small area mobile extender... some kind of box like you envision, set up in a strategic location that can hear the portables over the area that you need covered and get out to the main repeater system. That's presuming that your portables can hear the main repeater in this area... if not you'd need a full duplex extender which is a little more complex. |
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Quoted:
... ps: one thing –– why is this strictly on your nickel, and not the department's? ar-jedi If his Dept. is anything like mine, it's difficult to get them to spring for anything outside normal patrol stuff, especially one-off stuff. Our training budget was gone by this spring and won't be replenished until Sept., and most of us didn't get any special training this year. Our equipment budget is on an as-needed basis, rob Peter to buy Paul his gear. I bought my own armor plates/carrier/active shooter rig long before they got with the program of issuing at least one set per patrol car (we share fleet cars). And even that set isn't set up well. Even the nearby PD that equips its officers well (e.g., take home cars, NVGs for every officer) is having to cut way back due to the economy. Take home cars are to be restricted to those who live in the relatively small city limits. It's the life of .gov. Our dept. would love to buy more for us, just no money. Those of us with the skill are volunteering to install vehicle equipment so we can help cut the install cost. |
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Quoted:
Quoted:
... ps: one thing –– why is this strictly on your nickel, and not the department's? ar-jedi If his Dept. is anything like mine, it's difficult to get them to spring for anything outside normal patrol stuff, especially one-off stuff. Our training budget was gone by this spring and won't be replenished until Sept., and most of us didn't get any special training this year. Our equipment budget is on an as-needed basis, rob Peter to buy Paul his gear. I bought my own armor plates/carrier/active shooter rig long before they got with the program of issuing at least one set per patrol car (we share fleet cars). And even that set isn't set up well. Even the nearby PD that equips its officers well (e.g., take home cars, NVGs for every officer) is having to cut way back due to the economy. Take home cars are to be restricted to those who live in the relatively small city limits. It's the life of .gov. Our dept. would love to buy more for us, just no money. Those of us with the skill are volunteering to install vehicle equipment so we can help cut the install cost. Bingo. I'm lucky enough to work for people that don't mind progressive thought, as long as they don't have to pay for it. Excellent ideas, the long-range antenna is an excellent idea that I hadn't thought of. This is why I asked you guys, as I know y'all are the experts! For the person asking what sort of operations this would cover, mainly covert surveillance operations in hides, conducted prior to tac team raids, etc. Most often in woodland areas, but occasionally in improvised hide sites like vehicles or buildings. At least that's to start with. I'm trying to set up a sniper/observer component of our tac team, and a big selling point is intelligence gathering and surveillance. So, if I can make that part more effective, the whole idea is more likely to be successful. |
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Quoted: Wouldn't a tripod and yagi attract a little attention during surveillance work? I guess I was picturing hiding in the woods. And the rig I had in mind would be pretty tiny, since UHF yagi elements are pretty small. I figured the tripod didn't have to do anything more than hold the antenna on the correct azimuth at the correct polarization. You could probably lash it to a tree with the same effect. A little matte spray paint home-camo job would help. As someone else said, if he were disguised on the city street as a paper boy, a man-pack won't help either  Now a hot dog stand might have its advantages... |
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A mobile repeater would be the best way to go if one could be found cheap enough on the used market. Pevrs144 is aided by the fact that any unused police frequency can be used for low power surveillance on a secondary basis to any licensed users. So he could transmit to the portable on say 458.4250 mhz and have the repeater transmit on the police repeater input say 465.1750 mhz. His WT would always be on the main repeater output frequency of 460.1750 mhz. Mobile repeaters used to be standard equipment on some ambulances before the advent of cell phones. One of the main problems with public safety style WTs is that they don't have a BNC or other quick release on the antenna connection that would facilitate attaching a more efficient antenna. Building a manpack radio just might be the simplest way to have comms with dispatch.
I feel for your efforts. Acting on needs and not waiting for some official funding which may or may not materialize could save someone's life. My rescue squad's communcation system woud be the same now as 26 years ago had I not taken some initiative to improve it. RS |
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That Maxtrac is going to be pretty useless once you're required to go narrowband in the next couple years. Is your department staying with UHF or will they be moving to a different system when that time comes? Also, I'd think very hard about using encryption if this is to be used for surveillance. Just some more things to think about...
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Consider this option: .gov surplus. Check with your local .mil bases' surplus office and see if they have any suitable excess man-portable radio equipment. I can't warrant that they'll have what you need but if they DO, then its cost to your department will be "administrative costs only", provided of course that the equipment is excess property no longer needed by the government. The sheriff's department of my county operates five .gov surplus helicopters. At any given time two or even three of them are available for aerial details. This county and the agencies in it are always getting something from government surplus. It's a great deal for the county and saves tax dollars. And inevitably, some of the equipment is new or almost new. The reason why coverage down in the valley isn't very good when the repeater is on a mountaintop isn't a matter of power. It's a matter of the fact that the antenna's area of best coverage is laterally, not up and down. A gain antenna radiates strongest to the sides and all repeaters typically use gain antennas. You can be standing right under the antenna and not hear the repeater or have it hear you. Vehicular repeaters are a practical solution that doesn't require you to hump a heavy manpack radio. Some field tests would determine how well this option will work out for you, but I think that you'd agree that you'd rather carry a portable radio that weighs 12 ounces than a 10 pound (or more) manpack radio. CJ |
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Forget the mobile. I would look for a 4w in 20w out uhf amplifier similar to what hams use to boost HT power (ham stuff might work for you, not exactly legal) (manufactures would be TPL, RF concepts, Mirage, etc). That way you can still use a speaker mic or surveillance kit with the HT and have the ability to switch the amp on and off as needed. Plus, you can use your standard handheld batteries to still power the radio and have a measure of redundancy. Also, use the external antenna as much as possible to allow longer between battery re-supply. I work in the radio field and have been a ham for a while. Have done custom work for the .mil and .gov, so I have seen this request before. If you are looking to spend less that $15k per setup, the above in my post as well as the others above mine will get you there. Ty.
***edit to add––––If using mobile, it is a pain in the rectum to add in an external speaker easily and without disturbing your target. Reliabe and simple..T |
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If your doing any kind of surveillance you need to keep in mind that the bad guys are getting smarter and beginning to listen in on LEO freq.s. As many know this can even be done online in some areas. My suggestion would be to stick to a cell phone with a good headset and of course keep a radio on you for any close-ops that need to be done. We hit a house a few years back and the guy had a scanner sitting right beside his CCTV system. Dragging a bunch of gear in with you is the suck because you have to get it all out. Throw in having to get through a couple of fences and you are in for a long day. If cell service is unavailable you should consider the buddy system. Have back-up a mile or three down the road that can get you on direct and can relay to dispatch if nessecary. Something to look into also is gubmint grants for remote camera systems. Uncle Sugar got us one a few years ago that is just three shades of badass. Wireless trigger, IR camera smaller than a Redbull can, harddrive storage, and completely programmable to the point that you can tell it when to power on and off to record duration. We have deployed it for four days at a whack and it works like a charm. If it keeps me from peeing in a baggie, I'm happy. |
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How many guys do you have working a surveillance operation? There might not be enough bodies to do a relay. I had wanted a portable repeater for rescue operations in the rural areas of our county. The problem is that most people are not radio savvy enough to setup something like that and get it right. The fewer the switches and connections, the better. The portable radio box is the best way for the money.
RS |
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My guess is the main thing that's keeping your HT from working the repeater in these articular holes is the antenna. All other things being equal, the difference in perceived signal between a 5W radio and a 50W radio ain't all that much, and on FM every watt above what it takes to achieve full quieting is wasted making greenhouse gas that AlGore is trying so hard to make us buy (from him, let us not forget, so using less power will contribute to his starvation, an entirely good thing).
To me at least, there's no sense beating yourself up packing around a mobile rig and battery power if a 1 lb. antenna will do. The smallest UHF Yagi on a stick you can poke in the ground will more than likely do the job. Actually, you might even be better off with something like the cheap Radio Shack "Discone" scanner antenna. The advantage to that antenna is that orientation is not critical at all - it has an almost spherical radiation pattern. It has zero gain but that is still much better than any standard HT duck. All of that having been said, if you're not LOS to the repeater, no reasonable amount of RF power or antenna gain is going to change your geography. Line of sight from the radio perspective at UHF is something more than visual line of sight, but not a lot more. |