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| -rw-r--r-- | 08.-Passive-Radar.md | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/08.-Passive-Radar.md b/08.-Passive-Radar.md index 5ebb94d..0a1b786 100644 --- a/08.-Passive-Radar.md +++ b/08.-Passive-Radar.md @@ -144,7 +144,7 @@ Another example, if we are using a DAB transmitter as the illuminator, then we o ## RD Display within RD Display DVB-T Phenomenon -Sometimes you might see shrunken attenuated images of the entire RD display within the RD display itself. This is a phenomenon related to the way in which DVB-T signals are structured. +Sometimes when using DVB-T as an illuminator you might see shrunken attenuated images of the entire RD display within the RD display itself. This is a phenomenon related to the way in which DVB-T signals are structured for propagation distortion self-correction. It's possible that this could occur with other types of propagation distortion self-correcting signals. In brief, the DVB-T signal is constructed in the following way: In the frequency domain we have a vector with 8192 frequency bins. Each of these bins are sub-carriers. Some of these carriers are data carriers, some of them are pilot carriers. The data carriers are used to transfer the useful data (MPEG-2 stream) while the pilot carriers contain fixed modulation data which is preliminary known by the receiver. The transmitter assembles this frequency domain vector (called symbol table) and transforms it to the time domain with iFFT. After transformation it sends out the symbol and assembles the next symbol table. (Of course, there are a lot of other processes besides this main principle but those are not important at the moment). |