Receiving analog cell phones - possible !!!
"csb64918843" <[email protected]> Wed, 13 Jun 2007 19:46:23 -0000
| Newsgroups | gmane.recreation.radio.hardware.icomr2 |
|---|---|
| Message-ID | <[email protected]> |
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Hi to all,
I've found there is a way to receive 800MHz cell phone
transmissions on the IC-R2 receiver - without soldering
jumpers or other hardware hacks! One word : "intermod"
Until I can find a better explanation, here's briefly how it works:
When set to receive around 500MHz, the VFO runs at about [275-550]
Mhz, and the LO is twice the VFO, or [550-1100]MHz. This is
mixed with the RF signal, which gives the 1st IF of 266.7 MHz.
Apparently, in that range of frequencies (500), the LO would
contain some 3*VFO frequency component. Which allows a second
signal to be received. A simple calculation:
IC-R2 set to receive at 501.10 MHz. LO =3D RX + IF =3D 767.8 MHz.
Since LO is produced by 2*VFO, VFO =3D 383.9 MHz.
Now, the magic part:
the secondary RX signal is received using the 3*VFO component of
LO : LO=3D 3 * 383.9 =3D 1151.7 MHz.
Which gives a receiving frequency of: RX =3D LO - IF =3D 885.00 MHz=20
Right in the middle of the cell-band !
So, you can program your IC-R2 to search between approx. 490 and 510
MHz with a 20kHz stepping, which will let you scan the 800 cell-band
with its 30 kHz channel spacing.
Of course, reception isn't as good as it could be, but usually
the signal from the tower is fairly strong and comes in loud & clear.
Who wants a cell-enabled IC-R2 ? For sale, 300 $ !
CSB VA2CBW
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<p>Hi to all,<br>
I've found there is a way to receive 800MHz cell phone<br>
transmissions on the IC-R2 receiver - without soldering<br>
jumpers or other hardware hacks! One word : "intermod"<br>
<br>
Until I can find a better explanation, here's briefly how it works:<br>
When set to receive around 500MHz, the VFO runs at about [275-550]<br>
Mhz, and the LO is twice the VFO, or [550-1100]MHz. This is<br>
mixed with the RF signal, which gives the 1st IF of 266.7 MHz.<br>
Apparently, in that range of frequencies (500), the LO would<br>
contain some 3*VFO frequency component. Which allows a second<br>
signal to be received. A simple calculation:<br>
<br>
IC-R2 set to receive at 501.10 MHz. LO = RX + IF = 767.8 MHz.<br>
Since LO is produced by 2*VFO, VFO = 383.9 MHz.<br>
Now, the magic part:<br>
the secondary RX signal is received using the 3*VFO component of<br>
LO : LO= 3 * 383.9 = 1151.7 MHz.<br>
Which gives a receiving frequency of: RX = LO - IF = 885.00 MHz <br>
Right in the middle of the cell-band !<br>
<br>
So, you can program your IC-R2 to search between approx. 490 and 510<br>
MHz with a 20kHz stepping, which will let you scan the 800 cell-band<br>
with its 30 kHz channel spacing.<br>
<br>
Of course, reception isn't as good as it could be, but usually<br>
the signal from the tower is fairly strong and comes in loud & clear.<br>
<br>
Who wants a cell-enabled IC-R2 ? For sale, 300 $ !<br>
<br>
CSB VA2CBW<br>
<br>
</p>
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