Modem-satellite transmission with Doppler correction and E-SSA demodulation
A device in a population of devices arranged at a celestial body for transmitting data to a relay station orbiting the celestial body. The relay station and the population of devices are to travel with respect to one another such that the relay station is to receive signals that include the data in data packages from the population of devices. The device includes trajectory data of the relay station, a transmitter to use the trajectory data so as to transmit a signal that is part of the signals, a data processor, and a computer program which, when executing on the data processor, is to calculate a Doppler shift based upon the trajectory data, and modify the signal to thereby compensate for the Doppler shift of the signal that results from the travelling of the relay station and the population of devices with respect to one another.
1. A device in population of devices arranged spaced apart within an area on earth, and which are to transmit data to a low earth orbit (LEO) satellite orbiting earth, said LEO satellite to receive signals from said population of devices, said signals including the data in data packages, the device comprising:
a transmitter configured to transmit a signal that is part of said signals;
a data processor and a computer program which, when executing on said data processor, is to: calculate a relative speed of the LEO satellite with respect to the device, calculate a Doppler shift based upon trajectory data of said LEO satellite, modify said signal to thereby compensate for the Doppler shift of said signal that results from said LEO satellite and said population of devices travelling with respect to one another, use said trajectory data of said LEO satellite and use a relative position of said device to said LEO satellite to reduce transmission power by only transmitting the signal when said LEO satellite is either moving towards said population of devices or moving away from said population of devices, and set said transmitter to modify a frequency of transmission of said signal to correct said Doppler shift based upon a position of said LEO satellite and the calculated relative speed of said LEO satellite at a reception of said signal by said LEO satellite,
wherein, in response to calculating a positive Doppler shift, said computer program is configured to compensate for the Doppler shift of said signal by transmitting the signal at a lower frequency than its origin frequency, and
wherein, in response to calculating a negative Doppler shift, said computer program is configured to compensate for the Doppler shift of said signal by transmitting the signal at a higher frequency than its origin frequency.
2. The device of claim 1 , wherein said computer program is further configured to use said trajectory data to set said transmitter to either transmit said signal when said LEO satellite is moving towards said population of devices, or is moving away from said population of devices.
3. The device of claim 1 , wherein said transmitter comprises a modulator.
4. The device of claim 3 , wherein said modulator comprises an Enhanced Spread Spectrum Aloha (E-SSA) modulator.
5. A method for transmitting a part of data to a low earth orbit (LEO) satellite orbiting earth, the method comprising:
transmitting, via a device arranged on earth and which includes trajectory data of said LEO satellite, a signal to said LEO satellite, said device forming part of a population of devices that are arranged spaced apart within an area on earth, and said LEO satellite and said population of devices are configured to travel with respect to one another, wherein said signal forms part of signals transmitted by said population of devices, and includes signal data in data packages that is at least part of said data;
calculating a relative speed of the LEO satellite with respect to the device;
calculating, via said device, a Doppler shift based upon said trajectory data;
modifying, via said device, said signal to thereby compensate a Doppler shift of said signal that results from said LEO satellite and said population of devices travelling with respect to one another;
reducing transmission power by transmitting, using said trajectory data of said LEO satellite and using a relative position of said device to said LEO satellite, only when said LEO satellite is either moving towards said population of devices or moving away from said population of devices; and
modify a frequency of transmission of said signal to correct said Doppler shift based upon a position of said LEO satellite and the calculated relative speed of said LEO satellite at a reception of said signal by said LEO satellite,
wherein, in response to calculating a positive Doppler shift, compensating for the Doppler shift of said signal comprises transmitting the signal at a lower frequency than its origin frequency, and
wherein, in response to calculating a negative Doppler shift, compensating for the Doppler shift of said signal comprises transmitting the signal at a higher frequency than its origin frequency.
6. A non-transitory computer program product for transmitting part of data from a device to a low earth orbit (LEO) satellite orbiting earth, said device forming part of a population of devices arranged spaced apart within an area on earth and includes trajectory data of said LEO satellite, said population of devices and said LEO satellite travelling with respect to one another, and said population of devices configured to transmit data to said LEO satellite while said LEO satellite is orbiting earth, wherein said non-transitory computer program product, when executing on a data processor on said device, is to:
transmit, a signal to said LEO satellite, said signal forming part of signals transmitted by devices in said population of devices, said signal including signal data in data packages that is at least part of said part of data;
calculate a relative speed of the LEO satellite with respect to the device;
calculate a Doppler shift based upon said trajectory data;
modify said signal to thereby compensate a Doppler shift of said signal that results from said LEO satellite and said population of devices travelling with respect to one another;
reduce transmission power by transmitting, using said trajectory data of said LEO satellite and using a relative position of said device to said LEO satellite, only when said LEO satellite is either moving towards said population of devices or moving away from said population of devices; and
modify a frequency of transmission of said signal to correct said Doppler shift based upon a position of said LEO satellite and the calculated relative speed of said LEO satellite at a reception of said signal by said LEO satellite,
wherein, in response to calculating a positive Doppler shift, compensating for the Doppler shift of said signal comprises transmitting the signal at a lower frequency than its origin frequency, and
wherein, in response to calculating a negative Doppler shift, compensating for the Doppler shift of said signal comprises transmitting the signal at a higher frequency than its origin frequency.