Automotive Radar
Discussion
Try making sense of this:
www.tinyurl.com/83h4k
... must mean summat?
DVD
>> Edited by Dwight VanDriver on Monday 20th June 15:52
www.tinyurl.com/83h4k
... must mean summat?
DVD
>> Edited by Dwight VanDriver on Monday 20th June 15:52
Restrictions regarding the power/frequency output of short range radar for anti collision equipment. They've set a very low power output, but then how much do you need? The exclusion zones around Radio astronomy sites are pretty big though (Jodrell bank 9Km).
I'm guessing it's so that when these things become commonplace, someone doesn't "up the ante", and design one which would scramble gatso radar.
I'm sure a radio engineer will be along in a moment to give us the techie version though
Phil
Ps DVD, do you have to absorb this sort of stuff all the time?......must be a bloody nightmare!
I'm guessing it's so that when these things become commonplace, someone doesn't "up the ante", and design one which would scramble gatso radar.
I'm sure a radio engineer will be along in a moment to give us the techie version though
Phil
Ps DVD, do you have to absorb this sort of stuff all the time?......must be a bloody nightmare!
So we are going to have loads of big signs up remining us to switch our radar off near Jodrell Bank/Cambridge/several other places.
Presumably there will have to be air exclusion zones if not already in place to remind Flying Officer Kite in his crate that he must turn his radar off so he musn't be mistaken for an alien.
Perhaps we're expecting a Close Encounter.
And how the devil is this going to enforced?
The Court finds the defendant guilty that on 12 separate occasions during the month of xxxxx 20xx he did cause or permit emmission of radiation which interrupted a communication with Lord Vader.
25 years on each count to run concurrently.
Take him down.
Mind fully boggled.
FiF
>> Edited by Flat in Fifth on Monday 20th June 16:29
Presumably there will have to be air exclusion zones if not already in place to remind Flying Officer Kite in his crate that he must turn his radar off so he musn't be mistaken for an alien.
Perhaps we're expecting a Close Encounter.
And how the devil is this going to enforced?
The Court finds the defendant guilty that on 12 separate occasions during the month of xxxxx 20xx he did cause or permit emmission of radiation which interrupted a communication with Lord Vader.
25 years on each count to run concurrently.
Take him down.
Mind fully boggled.
FiF
>> Edited by Flat in Fifth on Monday 20th June 16:29
Flat in Fifth said:
So we are going to have loads of big signs up remining us to switch our radar off near Jodrell Bank/Cambridge/several other places.
I would guess the radio equipment will be linked to a GPS receiver, and will be pre-programmed to not transmit in the vicinity of the co-ordinates given of places such as Jodrell Bank.
philthy said:
They've set a very low power output, but then how much do you need?
Such high frequencies can only be transmitted to receivers within direct line of sight, unless bounced off reflectors(such as another car), and therefore only enough transmit power is needed to effect reliable operation.
In this case -41dbm is 79.43 nanoWatts
Hi DVD,
I'm not expert in this field but can offer a little bit of insight, hopefully without offending your intellect.
There are certain radio frequencies that are licencsed, and you are forbidden to transmit on these frequencies without said license.
One example of excemption being Computer Wireless which operates in the 2.4 and 5.4 giga Hertz bands. Anyone can use these frequencies and many of us do, however there are strict guidlines on how much power you can transmit with, which severley limits your range.
Looks to me like they are exemtping a block of the spectrum for deleopment purposes, epecially the clause about the vehicle not being reigstered or put into use in the community. As has been mentioend they've also set up some exclusion zones where the equipment may never be used.
That's about it really, not alot to get excited about, but evidently someone somewhere is wanting to test short range vehicle radar.
If you've got further questions plese ask away.
best
Ex
I'm not expert in this field but can offer a little bit of insight, hopefully without offending your intellect.
There are certain radio frequencies that are licencsed, and you are forbidden to transmit on these frequencies without said license.
One example of excemption being Computer Wireless which operates in the 2.4 and 5.4 giga Hertz bands. Anyone can use these frequencies and many of us do, however there are strict guidlines on how much power you can transmit with, which severley limits your range.
Looks to me like they are exemtping a block of the spectrum for deleopment purposes, epecially the clause about the vehicle not being reigstered or put into use in the community. As has been mentioend they've also set up some exclusion zones where the equipment may never be used.
That's about it really, not alot to get excited about, but evidently someone somewhere is wanting to test short range vehicle radar.
If you've got further questions plese ask away.
best
Ex
ledfoot said:
In this case -41dbm is 79.43 nanoWatts
Indeedy, this is very very short range stuff, and unless you've got an antenna the size of Jodrell Bank you are not going to hear it more than a few tens of metres away.
For reference 0dBm is classed as being the power emitted from a perfect point source antenaa (effectively the EIRP) when 1 milliWatt of power is applied.
It is a general rule of thumb that every 3dB change in power is a doubling (or halving if you are going negative) of the radiated power. As ledfoot has pointed out -41dBm is extremely low power.
best
Ex
theexcession said:
For reference 0dBm is classed as being the power emitted from a perfect point source antenaa (effectively the EIRP) when 1 milliWatt of power is applied.
Not quite correct....
0dBm =1mW
0dBm is purely a power reference point of 1 milliWatt (nothing to do with an antenna)
0dBi is a gain reference point for a hypothetical isotropic antenna which radiates or receives equally in all directions.
I must admit this is the first I've heard of this, which is a surprise as I'm a Techical Investigation Officer for Ofcom! Basically, the Wireless Telegraphy Acts (predominately S1/1 of the 1949 Act) say that anyone who uses a radio transmitter must have a licence. So that we all don't have to apply for licences to use the radio keyfobs to lock and unlock our cars, use a cordless telephone, etc, Statutory Instruments are introduced that exempt certain equipment from the need for a licence providing it complies with certain criteria.
This is the SI that exempts from licensing Collision Avoidance radar for use in cars. The bit about cars not yet registered/placed on the market, means that it can only be a factory fit option and not an after market thing.
It isn't to allow anyone to develop the system, that wouldn't require an SI, only the issue of a Non-Operational Development Licence. Presumably, someone has already been issued with one of these and has now produced a system that is ready to be fitted by car manufacturers. The SI needs to be issued to allow this to happen. The exclusion zones would almost certainly have to be controlled automatically by GPS. There is no way that a unit could be installed that could break the terms of the SI without the user being aware of it.
This is the SI that exempts from licensing Collision Avoidance radar for use in cars. The bit about cars not yet registered/placed on the market, means that it can only be a factory fit option and not an after market thing.
It isn't to allow anyone to develop the system, that wouldn't require an SI, only the issue of a Non-Operational Development Licence. Presumably, someone has already been issued with one of these and has now produced a system that is ready to be fitted by car manufacturers. The SI needs to be issued to allow this to happen. The exclusion zones would almost certainly have to be controlled automatically by GPS. There is no way that a unit could be installed that could break the terms of the SI without the user being aware of it.
Double Play said:
I think my personal favourite is:
"eirp" means effective isotropically radiated power
The simple way to understand "eirp" is to take a naked (OK no jokes now) torch bulb, it will effectively isotropically radiate light power in all directions equally. (OK forget the base, it's not there right!)
You can place a reflector behind it and get a huge increase in apparrent radiated power by making all the power "directional" and using it as a torch.
Radio antennas are the same except that a true isotropic radio antenna doesn't exist.
eirp is measured at a single point at a stated distance from the isotropic antenna, just like the light bulb.
Edited to make better sense!
>> Edited by 8Pack on Wednesday 22 June 02:29
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