I think that sunlight will have a much larger IR content then a flash light
would, so using a flash light bulb will likely not simulate intense background
light.
You could also try using optical filters to filter out light from your receiver
that is outside of the IR diode spectrum.

> Sean Breheny wrote:
> >
> > Also, does light emitted by an incandescant bulb have a significant noise
> > due to the discrete nature of the photons (like shot noise in electric
> > current)? How would one go about calculating the approximate amount of
> > noise from such a source? I have been using flashlights to simulate intense
> > background light (like the receiver is trying to pick out the source with
> > the sun as a backdrop) and the amount of noise I have been seeing is much
> > larger than I would expect due to electrical effects. I was wondering if I
> > am seeing real fluctuations in the light intensity.