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This a framework to test new ideas in transmission technology. Actual development is a LDPC-coder in

midamble
========


 One of the most important modules: in order to be able to decode a
received signal, one has to make an estimation of the channel which is
then used to 'correct' the signal. This module provides a 'midamble' to
create a well-known series of symbols, and a 'matched_filter', which
tries to recognise the midamble part and correct for the wrongly received
signal.


matched_filter
--------------

The receiving part of the midamble - the matched filter.

Inputs:
	SAMPLE_S12

outputs:
	SYMBOL_COMPLEX

Config:
	gain_control<int>: 0
		If set to 1, gain-control will be done

	index<int>: 0
		The index of the received user. If more than one user sent in the
		same timeslot, and each has a different index, each user can be
		estimated by giving the corresponding index here.

	num_ch_est<int>: 2
		Number of Channel estimates

	peak_location<int>: 32
		Where to put the peak_location. This is used because the channel
		is non-causal.

	type<int>: 3
		Type of the midamble. The following indexes are available:
		1 - 3GPP type 1 (192+64 = 256)
		2 - User Def    (512+32 = 544)
		3 - Midamble defined in Chinese WCDMA 128+16 = 144


Stats:
	flip_prob<double>:
		The BER, or flip_probability

	mafi<block_t>:
		A copy of the matched filter

	mid_amp<int>:
		The calculated midamble-amplitude

	mid_amp_old<int>:
		An old and simple way to calculate the mid_amp

	midamble<block_t>:
		A copy of the midamble

	noise_var<int>:
		The noise-variance

	noise_var_old<int>:
		An old and inaccurate way to calculate the variance

	offset<int>:
		How many samples we're off - the delay

	peak<SYMBOL_COMPLEX>:
		The highest tap

	peak_amp<int>:
		Peak-amplitude of the midamble

	peak_amp_stat[MAX_CH_EST]<int>:
		A midamble.^2

	snr<double>:
		Copy of snr_mid, deprecated

	snr_data<double>:
		Signal to noise ratio of the data-part 

	snr_mid<double>:
		Signal to noise ratio of the midamble

	snr_old<double>:
		mid_amp_old^2 / noise_var_old


midamble
--------

 A 3GPP midamble is implemented with a length of 256 symbols. It is
inserted in the middle of the received signal, so that it should reflect
most accuratly the changes from the channel.

Inputs:
	SYMBOL_COMPLEX

outputs:
	SYMBOL_COMPLEX

Config:
	amplitude<int>: 32767
		Amplitude of the midamble

	index<int>: 0
		The index of the user. Different users can send in the same
		timeslot using different indexes.

	type<int>: 3
		Type of the midamble. The following indexes are available:
		1 - 3GPP type 1 (192+64 = 256)
		2 - User Def    (512+32 = 544)
		3 - Midamble defined in Chinese WCDMA 128+16 = 144