From 850d5ca30cd10a3cf1edaf46234690c5dca3e5c4 Mon Sep 17 00:00:00 2001
From: Tim Kuester <tpkuester@gmail.com>
Date: Tue, 15 Apr 2014 16:59:53 -0400
Subject: documentation: Bit handling gotchas explained
---
gr-digital/python/digital/psk.py | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
(limited to 'gr-digital/python/digital/psk.py')
diff --git a/gr-digital/python/digital/psk.py b/gr-digital/python/digital/psk.py
index 1816ffb4ba..0e0c65ea2b 100644
--- a/gr-digital/python/digital/psk.py
+++ b/gr-digital/python/digital/psk.py
@@ -85,9 +85,15 @@ class psk_mod(generic_mod):
"""
Hierarchical block for RRC-filtered PSK modulation.
- The input is a byte stream (unsigned char) and the
- output is the complex modulated signal at baseband.
-
+ The input is a byte stream (unsigned char), treated as a series of packed
+ symbols. Symbols are grouped from MSB to LSB.
+
+ The output is the complex modulated signal at baseband, with a given number
+ of samples per symbol.
+
+ If "Samples/Symbol" is 2, and "Number of Constellation Points" is 4, a
+ single byte contains four symbols, and will produce eight samples.
+
Args:
constellation_points: Number of constellation points (must be a power of two) (integer).
mod_code: Whether to use a gray_code (digital.mod_codes.GRAY_CODE) or not (digital.mod_codes.NO_CODE).
@@ -113,8 +119,10 @@ class psk_demod(generic_demod):
"""
Hierarchical block for RRC-filtered PSK modulation.
- The input is a byte stream (unsigned char) and the
- output is the complex modulated signal at baseband.
+ The input is a complex modulated signal at baseband.
+
+ The output is a stream of bytes, each representing a recovered bit.
+ The most significant bit is reported first.
Args:
constellation_points: Number of constellation points (must be a power of two) (integer).
--
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