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#
# Copyright 2005 Free Software Foundation, Inc.
#
# This file is part of GNU Radio
#
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
__all__ = ['tv_rx']
import math
from usrpm import usrp_dbid
import db_base
import db_instantiator
def int_seq_to_str(seq):
"""convert a sequence of integers into a string"""
return ''.join (map (chr, seq))
def str_to_int_seq(str):
"""convert a string to a list of integers"""
return map (ord, str)
def control_byte_1(fast_tuning_p, reference_divisor):
c = 0x88
if fast_tuning_p:
c |= 0x40
if reference_divisor == 512:
c |= 0x3 << 1
elif reference_divisor == 640:
c |= 0x0 << 1
elif reference_divisor == 1024:
c |= 0x1 << 1
else:
assert 0
return c
def control_byte_2(target_freq, shutdown_tx_PGA):
if target_freq < 158e6: # VHF low
c = 0xa0
elif target_freq < 464e6: # VHF high
c = 0x90
else: # UHF
c = 0x30
if shutdown_tx_PGA:
c |= 0x08
return c
class db_tv_rx(db_base.db_base):
def __init__(self, usrp, which, first_IF, second_IF, inverted):
"""
Control Microtune 4937 based USRP daughterboard.
@param usrp: instance of usrp.source_c
@param which: which side: 0 or 1 corresponding to RX_A or RX_B respectively
@type which: int
"""
# sets _u and _which
db_base.db_base.__init__(self, usrp, which)
self._i2c_addr = (0x60, 0x61)[which]
self._first_IF = first_IF
self._second_IF = second_IF
self._reference_divisor = 640
self._fast_tuning = False
self._inverted = inverted
g = self.gain_range()
self.set_gain(float(g[0]+g[1]) / 2) # default gain is halfscale
self.bypass_adc_buffers(False)
# Gain setting
def _set_rfagc(self,gain):
assert gain <= 60 and gain >= 0
# FIXME this has a 0.5V step between gain = 60 and gain = 59.
# Why are there two cases instead of a single linear case?
if gain == 60:
voltage = 4
else:
voltage = gain/60.0 * 2.25 + 1.25
dacword = int(4096*voltage/1.22/3.3) # 1.22 = opamp gain
assert dacword>=0 and dacword<4096
self._u.write_aux_dac(self._which, 1, dacword)
def _set_ifagc(self,gain):
assert gain <= 35 and gain >= 0
voltage = gain/35.0 * 2.1 + 1.4
dacword = int(4096*voltage/1.22/3.3) # 1.22 = opamp gain
assert dacword>=0 and dacword<4096
self._u.write_aux_dac(self._which, 0, dacword)
def _set_pga(self,pga_gain):
assert pga_gain >=0 and pga_gain <=20
if(self._which == 0):
self._u.set_pga (0, pga_gain)
else:
self._u.set_pga (2, pga_gain)
def gain_range(self):
return (0, 115, 1)
def set_gain(self,gain):
assert gain>=0 and gain<=115
if gain>60:
rfgain = 60
gain = gain - 60
else:
rfgain = gain
gain = 0
if gain > 35:
ifgain = 35
gain = gain - 35
else:
ifgain = gain
gain = 0
pgagain = gain
self._set_rfagc(rfgain)
self._set_ifagc(ifgain)
self._set_pga(pgagain)
def freq_range(self):
return (50e6, 860e6, 10e3)
def set_freq(self, target_freq):
"""
@returns (ok, actual_baseband_freq) where:
ok is True or False and indicates success or failure,
actual_baseband_freq is the RF frequency that corresponds to DC in the IF.
"""
r = self.freq_range()
if target_freq < r[0] or target_freq > r[1]:
return (False, 0)
target_lo_freq = target_freq + self._first_IF; # High side mixing
f_ref = 4e6 / self._reference_divisor # frequency steps
divisor = int((target_lo_freq + (f_ref * 4)) / (f_ref * 8))
actual_lo_freq = (f_ref * 8 * divisor)
actual_freq = actual_lo_freq - self._first_IF;
if (divisor & ~0x7fff) != 0: # must be 15-bits or less
return (False, 0)
# build i2c command string
buf = [0] * 4
buf[0] = (divisor >> 8) & 0xff # DB1
buf[1] = divisor & 0xff # DB2
buf[2] = control_byte_1(self._fast_tuning, self._reference_divisor)
buf[3] = control_byte_2(actual_freq, True)
ok = self._u.write_i2c(self._i2c_addr, int_seq_to_str (buf))
return (ok, actual_freq - self._second_IF)
def is_quadrature(self):
"""
Return True if this board requires both I & Q analog channels.
This bit of info is useful when setting up the USRP Rx mux register.
"""
return False
def spectrum_inverted(self):
"""
The 43.75 MHz version is inverted
"""
return self._inverted
# hook this daughterboard class into the auto-instantiation framework
# With MT4937DI5-3x7702 with second downconversion
db_instantiator.add(usrp_dbid.TV_RX,
lambda usrp, which : (db_tv_rx(usrp, which, 43.75e6, 5.75e6, False),))
# With MT4937DI5-3x8680, and 3x8769 without second downconversion
db_instantiator.add(usrp_dbid.TV_RX_REV_2,
lambda usrp, which : (db_tv_rx(usrp, which, 44e6, 44e6, True),))
# With MT4937DI5-3x7901 without second downconversion, basically the same as tvrx2
db_instantiator.add(usrp_dbid.TV_RX_REV_3,
lambda usrp, which : (db_tv_rx(usrp, which, 44e6, 44e6, True),))
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