Figure 1.
IRNSS coverage area
Table 1.
Common parameters between GPS and IRNSS.
| System parameters | |
|---|---|
| Multiplexing | CDMA |
| Modulation | BPSK |
| Spreading code | Gold-cod 10 bits |
| Chip rate | 1.023 MHz |
| Code length | 1023 chips |
| Code period | 1 millisecond |
Table 2.
Difference between GPS vs IRNSS
| System parameter | IRNSS | GPS |
|---|---|---|
| Carrier center frequency | 1176.45 MHz | 1575.42 MHz |
| Coding scheme | Convolution + Interleaving | Parity check |
| Navigation data rate | 50 sps (50 sps equivalent to 25 bps) | 50 bps |
| System time | IRNSS system time | GPS time |
Figure 2.
IRNSS message frame’s structure
Figure 3.
Block diagram of developed SDR for IRNSS/NavIC signal
Figure 4.
Deep learning-based acquisition architecture for IRNSS/NavIC signal
Figure 5.
Process chain for message decoding.
Figure 6.
Experimental setup
Table 3.
USRP configuration.
| Parameters | Value |
|---|---|
| Output type | Complex int16 |
| Wire Format | Automatic |
| Sync | PC |
| Clock rate | 200 Mhz |
| Input type | short |
| Vector length | 2 |
| Append file | Overwrite |
| Value | 2000000 |
| Gain value | 80 |
| Antenna | TX/RX |
| Center Freq (Hz) | 1176450000 |
| Gain Type | Absolute (dB) |
| Bandwidth (Hz) | 0 |
Figure 7.
Check the input signal quality
Figure 8.
Acquisition CAF plots for all IRNSS PRNs at 12:31:37 May 23rd 2024
Figure 9.
Tracking plot for PRN 10 from 12:31:37 to 12:32:27 (50 seconds) on May 23rd 2024
Figure 10.
C/N0 values of all PRNs from 12:31:37 to 12:32:27 (50 seconds) on May 23rd 2024
Figure 11.
Navigation solution at 12:31:37
Figure 12.
Tracking plots for PRN 5 and PRN 7 on May 23rd 2024
Figure 13.
Navigation bits after FEC decoding of PRN 5 and PRN 7
Figure 14.
Acquisition results for different days
Figure 15.
CN0 for 24 hours on Jun 01st
Figure 16.
Skyplot for 24 hours
Figure 17.
Skyplot for 48 hours
Table 4.
Position errors on 24 hours of different days
| Position Error (m) | |||
|---|---|---|---|
| Timestamp | May 31st to Jun 01st | Jun 01st to Jun 02st | Jun 02nd to Jun 03rd |
| 08h08 | 33.799 | 26.603 | 24.391 |
| 09h08 | 33.799 | 24.701 | 29.853 |
| 10h08 | 25.282 | 29.419 | 27.301 |
| 11h08 | 24.077 | 30.654 | 26.301 |
| 12h08 | 19.548 | 29.672 | 22.105 |
| 13h08 | 23.021 | 26.279 | 25.620 |
| 14h08 | 26.312 | 28.145 | 29.931 |
| 15h08 | 81.092 | 30.279 | 116.789 |
| 16h08 | 18.969 | 37.771 | 287.028 |
| 17h08 | 16.200 | 26.711 | 34.795 |
| 18h08 | 29.095 | 25.321 | 44.743 |
| 19h08 | 26.686 | 19.269 | 27.064 |
| 20h08 | 27.063 | 16.008 | 21.467 |
| 21h08 | 24.116 | 19.926 | 20.831 |
| 22h08 | 18.608 | 23.237 | 21.786 |
| 23h08 | 19.233 | 19.428 | 13.061 |
| 00h08 | 21.068 | 30.044 | 16.809 |
| 01h08 | 28.057 | 17.627 | 28.040 |
| 02h08 | 22.837 | 28.461 | 29.899 |
| 03h08 | 28.939 | 30.769 | 33.448 |
| 04h08 | 27.689 | 60.949 | 42.273 |
| 05h08 | 23.232 | 30.203 | 26.902 |
| 06h08 | 29.191 | 26.937 | 20.437 |
| 07h08 | 21.802 | 26.068 | 23.469 |