Range of CHP Extenders...

[desdave]

Hopefully a Chippy can answer this as opposed to a scanner guy:

How far away from your unit can you be, and still be in range of your extender???

Someone once told me that it was about 200 feet... but this does not sound like it would be an acceptable distance in a situation such as a foot pursuit, or even a court appearance.

Any help would be appreciated.

[CRW]

I'm not saying you have bad intentions but this is directly related to officer safety and probably shouldn't be discussed in the open forum.

[KingFrankSam]

I agree with CRW, but I would add that it is significantly more than 200 feet.

[not5150]

Hopefully a Chippy can answer this as opposed to a scanner guy:

How far away from your unit can you be, and still be in range of your extender???

Someone once told me that it was about 200 feet... but this does not sound like it would be an acceptable distance in a situation such as a foot pursuit, or even a court appearance.

Any help would be appreciated.



I think the answer would fall under OPSEC issues.

[norcal625]

I was curious about the whole extender thing in general, I'm a cadet for a local pd and we don't have to hit some button to extend the range of our radios, just to get to the car and then from there to the antenna. Maybe I'm just not communcation system inclined. We are in California though someone might sue for that information cuse they think it should be public knowledge! (You can tell what I think of lawsuits :!: )

[desdave]

Wow... this was simply a curiousity question that seems to have been answered by 'significantly more than 200 yards'.

I am not a bad guy. Or a "bad" guy, for what its worth.

I simply heard that they could only be a very short distance from their unit which does indeed seem like an insane buttload more dangerous to officer safety then my rather basic question.

NORCAL625: Since the CHP uses low-band radios in the cars, they switch to an extender... which makes it so they do not have to use (fairly ineffective) low-band handhelds, instead they use a high-band handheld, which transmits to the car... then it gets beamed out via the more powerful car radio. What this really accomplishes is not having to radically add receiver sites throughout the area intended to be covered. The CHP uses an intricate set of low band recievers on hilltops, mountains and buildings throughout the state... but the number would be perhaps tripled if they did not use the extender system.

HORATIO: Thanks for your help, that was the rather simple answer I was looking for.

Dave

[BoySergeant]

Hopefully a Chippy can answer this as opposed to a scanner guy:

How far away from your unit can you be, and still be in range of your extender???

Someone once told me that it was about 200 feet... but this does not sound like it would be an acceptable distance in a situation such as a foot pursuit, or even a court appearance.

Any help would be appreciated.



Without getting too specific, I've easily out run my extender range in a foot pursuit. It can happen. Every radio system has 'dead' spots too...Thank heavens for cellular phones!

[CRW]

Wow... this was simply a curiousity question that seems to have been answered by 'significantly more than 200 yards'.

Glad you got your rather simple answer you were looking for.

I am not a bad guy. Or a "bad" guy, for what its worth.

Relax. I think the first thing I replied with was I think you don't have bad intentions. But you are not the only person reading this. Bad guys and "bad" guys do their homework just like we do because they hate going to jail almost more than we like taking them.

I started to reply----> They work at distances greater than 10 feet but less than two miles.:badgrin:

What would you rather have? An honest opinion from an officer about a topic in which you asked for a "Chippy" to respond or a smart a-- answer. I can give both.;)

[desdave]

What would you rather have? An honest opinion from an officer about a topic in which you asked for a "Chippy" to respond or a smart a-- answer. I can give both.;) [/quote]


Hmmm... how can I bow out of this gracefully....

Oh,

Like this.

Thanks for your (lack of) help!!

Cheers!

Dave

[SB 405]

Hey dave,Don't let something like this chase you away. I've asked a few questions myself over the last four months without having any idea I was getting into an Officer safety issue until I was told. You just have to realize these guys must keep a tight lip on certain issues about equipment,policy and procedure.

[Your Mentor]

Dave,
Please don't be offended. SB is right. There are things we simply can't discuss in an open forum. Some information is restricted by policy and other information is restricted by common sense. You obviously know how our vehicle system works and I know that information is not restricted. You are correct regarding the use of a low band - mid band linkage. It isn't to have a better handheld however. This is done for several reasons. Primarly for the boosted signal strength when we're out of our cars. The main secondary reason is so we can talk to allied agencies which use the Business band (mid band). As for the range of our extenders, there really is no such published range. This is because of the complexity of our vehicle systems. In the city it is short. In the open it is much greater. A number any of us could throw out there is nothing but a guess or estimate from our personal experience. But it really doesn't matter. We don't get very far from our cars. Remember; a CHP officer is pretty useless without a set of wheels. Okay, now finally, all the information on our "extenders" is pretty much on the Motorola website. We use the VHF version of the HT1000. I carry a personal JT1000. Neither model is in production anymore. All that info, however, is public.

[bcjack]

Mentor is right on the money...We use the VHF-High band frequency for our fire operations. The way the "Extenders" are configured, we can talk directly to a CHP Officer person to person without talking to either dispatch center. This is a rather informal practice here right now, but it sure works cool to be able to talk with a CHP Officer that is 1/4 to 1/2 mile away and let him or her know the fire engine is finished and we are leaving, and they can re-open the lane, without going through the following process:

1. Fire Engine calls the Fire Dispatcher and states they are finished at the scene, please notify CHP they can open the road
2. Fire Dispatcher calls CHP Dispatcher on the phone to relay the message.
3. CHP Dispatcher calls the Officers on the radio and passes on the message.
4. CHP Officer acknowledges the message.
5. CHP Dispatcher calls Fire Dispatcher on the phone to acknowledge the message.
6. Fire Dispatcher tells the Fire Engine Captain that the CHP has been notified and acknowledged the message.
7. Fire Engine leaves the scene
8. CHP Officers open the lane and traffic moves along "Normally" (Whatever that is)

We also can be directed where to park at an incident, cancel our response, or call for more help... :smile:

[Mick]

One thing crucial to having good transmission and reception is to move the handheld antenna away from your body, since your body acts as a capacitor. It's so easy to leave the radio as on your belt while talking through the external microphone. Once the radio is taken off the belt the range is greatly increased.
Hopefully a Chippy can answer this as opposed to a scanner guy:

How far away from your unit can you be, and still be in range of your extender???

Someone once told me that it was about 200 feet... but this does not sound like it would be an acceptable distance in a situation such as a foot pursuit, or even a court appearance.

Any help would be appreciated.

[dbduchene]

If no one minds I will address some of the info here as a ex ham and radio tech. First the reason for the extender is truly physics. A antenna needs to be a given length for a Frq. Speed of light in meters per sec (300,000,000 per sec) Devided by Frq in Cycles per sec times the velocity factor. (in a 1/4 wave about .9) I am lazy and do not feel like doiing the math but that means that at 42 meg it is between 5 and 6 feet. There are a few tricks that can be done and for HT's cut that to a third but we are still dealing with about a 2 foot long ducky ant. sticking in some poor persons arm pit and the lower in Frq the worse that these tricks to shorten the ant. work. So the state had a choice, change the whole system including trying to get new Frq's from the FCC Or a cross band repeter. The 1st Ht's when the extenders came out where one or 2 ch radio's. So that is the why. As to the range this is Radio folks there is no such answer. There is so many things that can afect this question. I understand that you thought that you where asking a simple question but in truth there is no simple answer. Over the history of the extender (cross band repeters) and including what is in the field today there are deferences that I will not even start going into. No one is really trying to be evasive there is no real answer to your question. I hope that this helps
Denis

[Your Mentor]

That last post went over my head at the speed of light.

[desdave]

I understood it... and since I started the whole ball rolling, it was appreaciated.

[dbduchene]

That last post went over my head at the speed of light.
I will try a little harder
Antennas have to me a given length for the freq. they work and have the correct impedance a given fraction of a wave length. The shortest that this will work at is one quater of a wave length. This means that a quater of a wave length addjusted for the fact that the radio waves slow down in metal as opposed to free space is 63 inchs at 42 megs. About the length of the whips that we used to see on the side of the cars. Now even if we reduce this by a forth (which at this freq we can not do) we still end up with a antenna that is 15 inchs long and works about as well as a wet noddle. :-) can you picture this on your belt every time that you sit in the car. SO when it was realized that CHP needed to have radios that worked some place besides on there cars there was a problem. At the freq. that they used it would just not work. But when you get into some remote areas there is a real addvantage to the low band radios. So the simple solutions was a cross band repeter in the car. This is what caused the Quote "extenders" to come about. Lets the HT's have a kind of short ant. As to the range of the extenders I can look at a given and give a pretty good guess and what affects this and why it works at a given distance one time and not another gets into some more of design and how "gain" is made in a ant. The short answer is that there is no such thing as a free ride. In another words when a ant. Makes gain it does it by focusing the engery in a area. The end results is that in that area the ANT. works better and out of that area it works worse. If in the field also known as the real world you get out of the area that the ant. focused and the range goes to H... This is why there is no answer the question of what is the range of the exteneder. I can tell you that I used to (in the old days) listen to the extender Freq. when I was on the open road on 2 radios and could tell how far away i was from one of your units ranging from 2 miles down to about 400 yards. I hope that I explianed a little better
D

[carcop]

Let me shed some light on this subject: I push the button and the person on the other end hears me ..... it's magic!:lol:

[dbduchene]

Let me shed some light on this subject: I push the button and the person on the other end hears me ..... it's magic!:lol:
I was told by a Instruckor once that the Def. of FM IS F***ING Magic you just reminded me of that and brought a smile to me.

[Mick]

Hello! FYI the extender frq. is VHF at 154.905 MHz, so a quarter wave antenna would need to be about 18 inches long, but with the existing 6 inch antenna with a coil inside it works very well. The extenders have never been on 42 MHz.
If no one minds I will address some of the info here as a ex ham and radio tech. First the reason for the extender is truly physics. A antenna needs to be a given length for a Frq. Speed of light in meters per sec (300,000,000 per sec) Devided by Frq in Cycles per sec times the velocity factor. (in a 1/4 wave about .9) I am lazy and do not feel like doiing the math but that means that at 42 meg it is between 5 and 6 feet. There are a few tricks that can be done and for HT's cut that to a third but we are still dealing with about a 2 foot long ducky ant. sticking in some poor persons arm pit and the lower in Frq the worse that these tricks to shorten the ant. work. So the state had a choice, change the whole system including trying to get new Frq's from the FCC Or a cross band repeter. The 1st Ht's when the extenders came out where one or 2 ch radio's. So that is the why. As to the range this is Radio folks there is no such answer. There is so many things that can afect this question. I understand that you thought that you where asking a simple question but in truth there is no simple answer. Over the history of the extender (cross band repeters) and including what is in the field today there are deferences that I will not even start going into. No one is really trying to be evasive there is no real answer to your question. I hope that this helps
Denis