A digital fsk equipment transmits bipolar return to zero data. when sending a sequence of alternating ones and zeros how many different frequenies will be transmitted?
The fsk is actually sending mark and space signals, isn't it? The actual frequncies depnends on the technique of modulation (quad fsk?) and the filters on the transmitter at the output. Ideally, there are two frequencies involved, but in practice, there are more. Actually, in practice, the mark and space spectrum is not a single frequency, but spectrum. The bandwidth of the mark/space signal is dependent on keying frequency. So you have several parameters which matter. Normally, we try to filter these bandwidths, mainly to get the power into the center information band (either mark or space), but it does also reduce interference. In my modem on my HAM radio station, I have a built in active filter to do this.
http://rfwireless.rell.com/pdfs/TN_WJfsk.pdf
To determine the number of different frequencies transmitted when using bipolar return to zero data in FSK (Frequency Shift Keying), we need to understand FSK modulation and the characteristics of the transmitted signal.
In FSK modulation, different frequencies are used to represent different binary symbols. Each binary symbol (0 or 1) is mapped to a specific frequency. In bipolar return to zero data, the binary sequence consists of alternating ones and zeros.
In this case, there are typically two frequencies involved: a "mark" frequency and a "space" frequency. The mark frequency represents a binary 1, while the space frequency represents a binary 0. The number of different frequencies transmitted is determined by the number of symbols or bits being transmitted.
However, it's worth mentioning that in practice, the mark and space signals are not represented by a single frequency but have a spectrum of frequencies due to practical constraints such as modulation techniques, filters, and bandwidth requirements. The actual frequencies used and the spectrum bandwidth depend on the specific FSK modulation technique and the design of the transmitter.
Therefore, the answer to the question of how many different frequencies will be transmitted in the case of alternating ones and zeros in bipolar return to zero FSK depends on the specific implementation and modulation technique being used, as well as the design of the transmitter and its filters.
For further details, you can refer to the provided link which discusses FSK modulation in more depth.