rpitx/csdr
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

Documentation++

Browse source
This commit is contained in:
ha7ilm 2016-01-12 23:19:35 +01:00
parent 95777e29af
commit fc19371a3e
1 changed files with 21 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
README.md
View file

@ -189,7 +189,7 @@ Internally, a sine and cosine wave is generated to perform this function, and th
shift_addition_cc <rate> shift_addition_cc <rate>
Operation is the same as with `shift_math_cc`. Operation is the same as for `shift_math_cc`.
Internally, this function uses trigonometric addition formulas to generate sine and cosine, which is a bit faster. (About 4 times on the machine I have tested it on.) Internally, this function uses trigonometric addition formulas to generate sine and cosine, which is a bit faster. (About 4 times on the machine I have tested it on.)
@ -203,6 +203,20 @@ Operation is the same as with `shift_math_cc`.
Internally, this function uses a look-up table (LUT) to recall the values of the sine function (for the first quadrant). Internally, this function uses a look-up table (LUT) to recall the values of the sine function (for the first quadrant).
The higher the table size is, the smaller the phase error is. The higher the table size is, the smaller the phase error is.
shift_addfast_cc <rate>
Operation is the same as for `shift_math_cc`.
Internally, this function uses a NEON-accelerated algorithm on capable systems, so it is advised to use this one on ARM boards.
shift_unroll_cc <rate>
Operation is the same as for `shift_math_cc`.
This uses a modified algoritm that first stores a vector of sine and cosine values for given phase differences.
The loop in this function unrolls quite well if compiled on a PC. It was the fastest one on an i7 CPU during the tests.
decimating_shift_addition_cc <rate> [decimation] decimating_shift_addition_cc <rate> [decimation]
It shifts the input signal in the frequency domain, and also decimates it, without filtering. It will be useful as a part of the FFT channelizer implementation (to be done). It shifts the input signal in the frequency domain, and also decimates it, without filtering. It will be useful as a part of the FFT channelizer implementation (to be done).
@ -347,6 +361,12 @@ The actual number of padding samples can be determined by running `cat csdr.c |
It exchanges the first and second part of the FFT vector, to prepare it for the waterfall/spectrum display. It should operate on the data output from `logpower_cf`. It exchanges the first and second part of the FFT vector, to prepare it for the waterfall/spectrum display. It should operate on the data output from `logpower_cf`.
setbuf <buffer_size>
If the environment variable `CSDR_DYNAMIC_BUFSIZE_ON` is set to 1, then you can use this command to set the input buffer size for the next `csdr` process in the chain.
#### Control via pipes #### Control via pipes
Some parameters can be changed while the `csdr` process is running. To achieve this, some `csdr` functions have special parameters. You have to supply a fifo previously created by the `mkfifo` command. Processing will only start after the first control command has been received by `csdr` over the FIFO. Some parameters can be changed while the `csdr` process is running. To achieve this, some `csdr` functions have special parameters. You have to supply a fifo previously created by the `mkfifo` command. Processing will only start after the first control command has been received by `csdr` over the FIFO.