CCTV Cameras

[JohnW2]

That is certainly not rf in TV terms.

He didn't claim it was, only that it was "not transmitting by RF"

If you don't think that 6 MHz qualifies as "RF", I wonder what you would call it? It's certainly above "AF" and "Ultrasound" frequencies, and certainly less than microwaves and all shorter wavelengths of EM radiation

In fact, as regards "RF in TV terms", I was brought up on (a small number of hours per day of) BBC on Band 1, Channel 1, which was broadcast on frequencies far less than an order of magnitude greater than 6 MHz (if I recall, audio on 41.5 MHz and video on 45 MHz - although, of course, they were Mc/s in those days!) - and I'm sure no-one would have argued that that was not "RF"

... and, of course, my earliest amateur radio activity was on the 1.8 - 2.0 Mc/s (or MHz) band - so wasn't that "RF", either?

Kind Regards, John

 

[AstonHill]

Dose any know who the frequency range of this camera yet?

 

[DetlefSchmitz]

Dose any know who the frequency range of this camera yet?

It is a base-band composite video signal. You should not get distracted by John's reminiscences of amateur radio.

 

[JohnW2]

It is a base-band composite video signal. You should not get distracted by John's reminiscences of amateur radio.

It wasn't my intention to distract. I was merely responding to a comment that a composite video signal is "nor FR" - and, as I said, if it's not "RF" what else can/should one call it?

Definitions of RF vary but generally go from a bit above AF (and what many would call 'ultrasonic') up to where other specifically-named types of EM radiation start - probably usually IR. For what it's worth, Wikipedia says that "RF" is from 'around 20 kHz' to 'around 500 GHz' - which is consistent with what I've just said.

The relevant on-topic point for the OP is that, before the distraction appeared, as I and others said to him, a short legth of virtually any cable should give some sort of picture (even if 'not good') - so, despite what he had been told, he didn't need any particular/'special' type of cable.

Kind Regards, John

 

[AstonHill]

It is a base-band composite video signal. You should not get distracted by John's reminiscences of amateur radio.

But its got everything to do with frequency; The higher the frequency the more resistance the cable needs to be and the fitting need to be better to

 

[JohnW2]

But its got everything to do with frequency;

As I said, a composite video signal can go up to a frequency of 6 Mhz (sometimes even more) but may be as low as around 2 MHz

The higher the frequency the more resistance the cable needs to be

That is total nonsense

and the fitting need to be better to

... that becomes true at very high frequencies, but not relevant to what you are dealing with or want to achhive.

Kind Regards, John

 

[AstonHill]

as I and others said to him, a short legth of virtually any cable should give some sort of picture (even if 'not good') - so, despite what he had been told, he didn't need any particular/'special' type of cable.

But we did get a signal into the TV. Infact it was that bad that we could not see anything but the old snow effect from analog TV. (And even that was not a full screen) The point is we need to get a decent picture to know if the cameras are any good or not

 

[AstonHill]

That is total nonsense

No its not! If you have a frequency signal and you double its pitch (so this could be a radio signal or sound from a guitar) you shorten its radio wave by half. So dynamically it has to travel twice the distance, bit like the trains and little men on the Hornby set

 

[Harry Bloomfield]

The higher the frequency the more resistance the cable needs to be and the fitting need to be better to

Rubbish, I think you are becoming confused with impedance matching. For the strongest and best quality signal, no matter what the type of signal, things need to be designed for a certain impedance standard. That design principle includes everything on the circuit - the items at the ends of the circuit (in your case your camera and TV input), the plugs, the sockets and the actual cable itself. For what you are attempting, the poor matching will have little impact.

 

[JohnW2]

No its not! If you have a frequency signal and you double its pitch (so this could be a radio signal or sound from a guitar) you shorten its radio wave by half. So dynamically it has to travel twice the distance, bit like the trains and little men on the Hornby set

That's even more total nonsense but, even if it weren't why on earth would higher frequency (hence, as you say, shorter wavelength) need higher resistance cable?

Kind Regards, John

 

[Harry Bloomfield]

No its not! If you have a frequency signal and you double its pitch (so this could be a radio signal or sound from a guitar) you shorten its radio wave by half. So dynamically it has to travel twice the distance, bit like the trains and little men on the Hornby set

There seems to be major hole in your understanding, but then if you think you understand these things, why are you on here asking very basic questions?

 

[AstonHill]

see attachment

 

[JohnW2]

see attachment

That's no news to any of us. What one earth is your point?

As an early warning, I don't know about others but I'm getting quite close to the "I'm out" point as far as this thread is concerned.

Kind Regards, John

 

[AstonHill]

My fitting turned up in the end and I connected it to the phono cable and plugged it all in

As I turn the power on the camera, there is no signal for a short while, but after a while there is a clicking noise and I get an image on the tV. However this is not for long and goes back to a black fuzzy screen

 

[DetlefSchmitz]

Probably got the wrong frequency.