it states that the maximum transmission distance is calculated by:
**broken link removed**
The problem is that E = volts per meter of the receiver.
I can't determine volts/meter for my receiver.
Could I calculate the distance some other way?
The thing that is the most common between my transmitter and my receiver is that they both contain an LC tank circuit.
I have heard of inductive coupling (using a transformer between amplifier stages). could I use that to form a distance equation?
when you think about it, the transmitter and the receiver are inductively coupled to each other, wirelessly.
but whatever the case is, I need a simpler equation for maximum transmission distance.
because right now, the way I see it, my 3V transmitter can transmit 2.8KM if my receiver has a 20uV/m sensitivity.
and please answer, because I don't want to jam anyones signal.
Tony Van Roon's 3V FM transmitter is very low powered and has a range to a very sensitive FM radio of about 100 feet, only to across my street.
My Rev4 FM transmitter uses a 9V supply and an RF output amplifier for much higher output power and its range is more than 2km to a very sensitive FM radio.
If the 3V transmitter uses 10mA then its supply power is 30mW with a brand new battery. My FM transmitter uses 54mA then its supply power is 486mW.
The 3V transmitter is about 40% efficient because it operates in class-A. My transmitter is about 70% efficient because its RF amplifier operates in class-C. Crunching the numbers reveals that my FM transmitter is 28 times more powerful than the little guy.
Good FM radios have an RF amplifier and a very high gain IF amplifier for their high sensitivity of close to 1uV/m. Cheap ones don't have an RF amplifier but the high gain of their IF amplifier still allows them to perform pretty well with a sensitivity of about 10 to 20uV/m.
Your FM receiver doesn't have a high gain IF amplifier. It also doesn't have an FM detector. It might have a sensitivity of only 100 to 200uV/m. Surely it will also reduce the range of your transmissions. 15 feet? :wink:
I have uploaded a rather stripped (non-working) version of my superregen detector.
I was wondering if I could calculate the sensitivity of it by the following equation:
Z / (Z + R2 + R1) * V
where Z is the impedance ofthe tank circuit (inductor and capacitor in parallel), and V is the supply voltage.
maybe then I can get volts/meter
Why do I think it works, because I'm dealing with a forward biased diode between base and emitter of the NPN, and I could just ignore the collector which is why R1 and R2 are added together.
Your equation has nothing to do with a radio's sensitivity. The sensitivity is determined by the actual voltage gain of the circuit.
Since your super-regen oscillates instead of amplifying, I don't think there is an equation for its sensitivity.
Just build it and measure its range. 15 feet? :wink:
Your equation has nothing to do with a radio's sensitivity. The sensitivity is determined by the actual voltage gain of the circuit.
Since your super-regen oscillates instead of amplifying, I don't think there is an equation for its sensitivity.
Just build it and measure its range. 15 feet? :wink:
I have received all FM stations a normal radio in hamilton (my city) can receive. as for TV stations, I can receive the local one (CHTV), and I can barely receive Toronto's new station, CKCO.
so maybe I can get an approximate volts/meter on that.
I can't conclude that I can transmit 60 or so km to my receiver, because I don't know the exact power the transmitters are transmitting.
No. That is more of us in Mississauga. Hamilton is a half-hour or less drive away. It stinks there because of the steel-making plants. What are they burning???