Ironic
Electrical
- Apr 30, 2010
- 2
Hello, this is my first post and i hope it´s in the right place.
My objective is to transmit voice and data trough standard transmitters, like the ones found in ebay, with power of a few watts. This is to be used in urban environments, so wall penetration is one of the more important aspects.
The data signal can be of a low bitrate(1kbps is enough), and voice doesn´t have to be of high quality and can be mono.
Telephone lines since are designed for human voice transmit up to 4Khz, while AM and FM transmitters since are designed for music should transmit up to 20Khz(human hearing limit).
My plan is to use a microcontroler to encode the binary data as FSK in a frequency maybe around 10Khz, and add it to the voice signal. At the receiver, filters would separate the 2 signals, and another microcontroler would decode the digital data(maybe using a pll chip).
For me the data reliability would be the most important thing. Would prefer the loose voice first, in case of bad reception. The 1kbps rate would allow me to use redundancy/error correction codes.
For building penetration should i go for AM or FM? (AM usually lower frequency-better penetration?)
I´ve also looked in to RDS, but was discouraged by the fact that since it´s an harmonic, power is lower. (I usually loose RDS on car radio in areas of low coverage, first, and keep hearing music- the opposite of what i want...)
Don´t want to burden anyone, but would appreciate suggestions/critics, and to be pointed in the right direction. The details i think i can workout on my own.
Thank You
My objective is to transmit voice and data trough standard transmitters, like the ones found in ebay, with power of a few watts. This is to be used in urban environments, so wall penetration is one of the more important aspects.
The data signal can be of a low bitrate(1kbps is enough), and voice doesn´t have to be of high quality and can be mono.
Telephone lines since are designed for human voice transmit up to 4Khz, while AM and FM transmitters since are designed for music should transmit up to 20Khz(human hearing limit).
My plan is to use a microcontroler to encode the binary data as FSK in a frequency maybe around 10Khz, and add it to the voice signal. At the receiver, filters would separate the 2 signals, and another microcontroler would decode the digital data(maybe using a pll chip).
For me the data reliability would be the most important thing. Would prefer the loose voice first, in case of bad reception. The 1kbps rate would allow me to use redundancy/error correction codes.
For building penetration should i go for AM or FM? (AM usually lower frequency-better penetration?)
I´ve also looked in to RDS, but was discouraged by the fact that since it´s an harmonic, power is lower. (I usually loose RDS on car radio in areas of low coverage, first, and keep hearing music- the opposite of what i want...)
Don´t want to burden anyone, but would appreciate suggestions/critics, and to be pointed in the right direction. The details i think i can workout on my own.
Thank You
