On 4 Aug 2016 at 0:57, Neil wrote:

> I built a quick device for a friend that lets a receptionist send=20
> messages from a PC to a desktop display device, and vice-versa with a=20
> handful of canned responses.  The PC side uses VB to serial (via USB),=20
> to a USB-to-serial interface, then a 433 Mhz serial module, through an=20
> IPEX-to-RP-SMA interface, to a short whip antenna.  The desktop display=20
> device also has the same 433 Mhz serial module (controlled by an=20
> Arduino), to the same IPEX-to-RP-SMA interface cable, then to an=20
> identical whip antenna.
>=20
> I'm not getting the range necessary... I'm getting 35-ish feet indoors=20
> (through one wall), and need about 100 feet indoors (in an office=20
> through a glass wall).  I've tried a 433 Mhz PCB antenna, but that got=20
> me less distance than the whip antennas.  And the whip antennas are=20
> listed as being for 433 Mhz.
>=20
> Any clues on how to get better distance?  I'm looking for 433Mhz=20
> amplifiers, but they're a bit pricey.  I'm short on time, so hoping to=20
> find a ready-made solution (if an amp is necessary), rather than having=20
> to build one.

Without changing any hardware: Reducing data rate can increase distance. Do=
n't=20
know if modules are doing encoding for you... if not then may need to add a=
=20
preamble so receiver can tune-in/stabilise before data starts coming, may n=
eed to=20
"whiten" the data if longish stretches of all 0 or all 1 bits are common in=
 the data=20
(how you do that can range from complicated and comprehensive to simple but=
=20
limited).


--=20
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