System and method for chirp-based transmission

1. An electromagnetic transmission system, comprising:

M first chirp generators, each operating at a first frequency, each of the M first chirp generators being configured to generate P first digital chirp sample points comprising (1/M) th of a first digital chirp signal having a first ramp rate;

M second chirp generators, each operating at the first frequency, each of the M second chirp generators being configured to generate P second digital chirp sample points comprising (1/M) th of a second digital chirp signal having a second ramp rate;

M adders, each configured to add the P first digital chirp sample points to the P second digital chirp sample points, respectively, to generate P combined digital chirp sample points;

a parallel-in serial-out register configured to receive the P combined digital chirp sample points in parallel at the first frequency, and configured to output the P combined digital chirp sample points in series as (1/M) th of the digital chirp signal at a second frequency; and

a digital-to-analog converter operating at the second frequency and configured to convert the digital chirp signal into an analog chirp signal,

wherein M and P are integers greater than 1,

wherein the second frequency is at least M times the first frequency, and

wherein the second ramp rate is different from the first ramp rate.

2. The electromagnetic transmission system of claim 1 , further comprising:

an antenna configured to transmit the analog chirp signal.

3. The electromagnetic transmission system of claim 1 , wherein the chirp signal is modulated with data.

4. The electromagnetic transmission system of claim 3 , wherein the modulation is one of BPSK, QPSK, or QAM encoding.

5. An electromagnetic transmission system, comprising:

M first chirp generators, each operating at a first frequency, each of the M first chirp generators being configured to generate an i th first digital chirp portion comprising (1/M) th of a first digital chirp signal having a first ramp rate and a first starting frequency;

M second chirp generators, each operating at the first frequency, each of the M second chirp generators being configured to generate an i th second digital chirp portion comprising (1/M) th of a second digital chirp signal having a second ramp rate and a second starting frequency;

M adders, each configured to add the i th first digital chirp portion to the i th second digital chirp portion to generate an i th combined digital chirp portion;

a parallel-in serial-out register configured to receive the M combined digital chirp portions in parallel at the first frequency, and configured to output the M combined digital chirp portions in series as a combined digital chirp portion signal at a second frequency; and

a digital-to-analog converter operating at the second frequency and configured to convert the combined digital chirp signal portion into a combined analog chirp signal portion,

wherein M is an integer greater than 1,

wherein i is an index that goes from 1 to M,

wherein the second frequency is M times the first frequency,

wherein the first chirp signal and the second chirp signal are orthogonal or nominally orthogonal, and

wherein the second ramp rate is different from the first ramp rate.

6. The electromagnetic transmission system of claim 5 , wherein the second starting frequency is different from the first starting frequency.

7. The electromagnetic transmission system of claim 5 , further comprising:

an antenna configured to transmit the combined analog chirp signal portion.

8. The electromagnetic transmission system of claim 5 , wherein

the first chirp signal is modulated with first data, and

the second chirp signal is modulated with second data.

9. The electromagnetic transmission system of claim 8 , wherein

the first and second chirp signals are modulated using one of BPSK, QPSK, or QAM encoding.

10. A method of generating an electromagnetic signal, comprising:

generating M first digital chirp portions at a first frequency, each of the M first digital chirp portions comprising P sample points that make up (1/M) th of a first digital chirp signal having a first ramp rate and a first starting frequency;

generating M second digital chirp portions at the first frequency, each of the M second digital chirp portions comprising P sample points that make up (1/M) th of a second digital chirp signal having a second ramp rate and a second starting frequency;

adding corresponding first digital chirp portions to corresponding second digital chirp portions to generate M combined digital chirp portions at the first frequency;

outputting the M combined digital chirp portions in series as a combined digital chirp signal portion at a second frequency; and

converting the combined digital chirp signal portion into a combined analog chirp signal portion,

wherein P and M are integers greater than 1,

wherein the second frequency is M times the first frequency,

wherein the first chirp signal and the second chirp signal are orthogonal or nominally orthogonal, and

wherein the second ramp rate is different from the first ramp rate.

11. The electromagnetic transmission system of claim 10 , wherein the second starting frequency is different from the first starting frequency.

12. The method of claim 10 , further comprising:

modulating the first chirp signal with first data, and

modulating the second chirp signal with second data.

13. The method of claim 12 , wherein

the first and second chirp signals are modulated using one of BPSK, QPSK, or QAM encoding.