Frequency scheme for data transmission systems

1. A data transmission system, comprising:

at least two stations between which data bursts being interchanged via radio, said stations including:

a first station having a first transmitter for up-mixing the data bursts from baseband to a first channel mid-frequency and for transmitting them, and a first receiver receiving the data bursts at a second channel mid-frequency and down-mixing them to an intermediate frequency, said first station having a first local oscillator producing a first local frequency required for up-mixing from the baseband to the first channel mid-frequency and required for down-mixing from the second channel mid-frequency to the intermediate frequency; and

a second station having a second transmitter up-mixing the data bursts from the baseband to the second channel mid-frequency and transmitting them, and a second receiver receiving the data bursts at the first channel mid-frequency and down-mixing them to the intermediate frequency, a frequency hop between the first channel mid-frequency used for a downlink transmission from said first station to said second station and the second channel mid-frequency used for an uplink transmission from said second station to said first station has a magnitude corresponding to a magnitude of the intermediate frequency, said second station having a second local oscillator producing a second local frequency required for up-mixing from the baseband to the second channel mid-frequency and required for down-mixing from the first channel mid-frequency to the intermediate frequency.

2. The data transmission system according to claim 1 , wherein the first channel mid-frequency is chosen on a pseudo-random basis.

3. The data transmission system according to claim 1 , wherein data is transmitted using a frequency hopping method, with the channel mid-frequency being changed after each transmitted data burst.

4. The data transmission system according to claim 1 , wherein the channel mid-frequency is constant during a transmission of a data burst.

5. The data transmission system according to claim 1 , wherein a difference between the first channel mid-frequency and the second channel mid-frequency is a noninteger multiple of channel separation.

6. The data transmission system according to claim 1 , wherein said first and second local oscillators are frequency-stabilized by a phase locked loop.

7. The data transmission system according to claim 1 , further comprising means for producing guard time intervals between various data bursts.

8. The data transmission system according to claim 7 , wherein a length of a guard time interval between the downlink transmission from said first station to said second station and the uplink transmission from said second station to said first station corresponds approximately to a clock drift of a corresponding one of said first and second local oscillators.

9. The data transmission system according to claim 1 , wherein said first and second stations have means for producing identification information at a start of a transmission of each data burst.

10. The data transmission system according to claim 1 , wherein transmission frequencies within an ISM frequency band are used.

11. The data transmission system according to claim 1 , wherein said first station and said second station are part of a piconetwork.

12. The data transmission system according to claim 1 , wherein one of said first and second stations is a base station and the other is a mobile station.

13. The data transmission system according to claim 1 , wherein the data transmission system can be used in cordless communication systems, in computer-controlled entertainment systems, or in computer-controlled games systems.

14. A method for data transmission between at least two stations via radio paths using a frequency hopping method, which comprises the steps of:

up-mixing from baseband and transmitting a first signal from a first station to a second station at a first channel mid-frequency;

receiving the first signal in the second station and down-mixing the first signal to an intermediate frequency;

up-mixing from the baseband and transmitting a second signal from the second station to the first station at a second channel mid-frequency differing from the first channel mid-frequency by the intermediate frequency;

receiving the second signal in the first station and down-mixing the second signal to the intermediate frequency;

producing a first local frequency required for up-mixing from the baseband to the first channel mid-frequency and required for down-mixing from the second channel mid-frequency to the intermediate frequency using a first local oscillator in the first station; and

producing a second local frequency required for up-mixing from the baseband to the second channel mid-frequency and required for down-mixing from the first channel mid-frequency to the intermediate frequency using a second local oscillator in the second station.

15. The method according to claim 14 , which further comprises choosing the first channel mid-frequency on a pseudo-random basis.

16. The method according to claim 14 , which further comprises transmitting data using the frequency hopping method, and changing the channel mid-frequency after each transmitted data burst.

17. The method according to claim 14 , which further comprises setting the channel mid-frequency to remain constant during the transmission of a data burst.

18. The method according to claim 14 , which further comprises including guard time intervals between the transmission of the various data bursts.

19. The method according to claim 14 , which further comprises choosing a noninteger multiple of channel separation as the intermediate frequency.

20. A data transmission system, comprising:

at least two stations between which data bursts being interchanged via radio, said stations including:

a first station having a first transmission means for up-mixing the data bursts from baseband to a first channel mid-frequency and transmitting them, and a first reception means for receiving the data bursts at a second channel mid-frequency and down-mixing them to an intermediate frequency, said first station having a first local oscillator producing a first local frequency required for up-mixing from the baseband to the first channel mid-frequency and required for down-mixing from the second channel mid-frequency to the intermediate frequency; and

a second station having a second transmission means for up-mixing the data bursts from the baseband to the second channel mid-frequency and transmitting them, and a second reception means for receiving the data bursts at the first channel mid-frequency and down-mixing them to the intermediate frequency, a frequency hop between the first channel mid-frequency used for a downlink transmission from said first station to said second station and the second channel mid-frequency used for an uplink transmission from said second station to said first station has a magnitude corresponding to a magnitude of the intermediate frequency, said second station having a second local oscillator producing a second local frequency required for up-mixing from the baseband to the second channel mid-frequency and required for down-mixing from the first channel mid-frequency to the intermediate frequency.