//------------------------------------------------------------------------------
// transmit() -- send radar emissions
//------------------------------------------------------------------------------
void Radar::transmit(const LCreal dt)
{
BaseClass::transmit(dt);
// Transmitting, scanning and have an antenna?
if ( !areEmissionsDisabled() && isTransmitting() ) {
// Send the emission to the other player
Emission* em = new Emission();
em->setFrequency(getFrequency());
em->setBandwidth(getBandwidth());
const LCreal prf1 = getPRF();
em->setPRF(prf1);
int pulses = static_cast<int>(prf1 * dt + 0.5);
if (pulses == 0) pulses = 1; // at least one
em->setPulses(pulses);
const LCreal p = getPeakPower();
em->setPower(p);
em->setMaxRangeNM(getRange());
em->setPulseWidth(getPulseWidth());
em->setTransmitLoss(getRfTransmitLoss());
em->setReturnRequest( isReceiverEnabled() );
em->setTransmitter(this);
getAntenna()->rfTransmit(em);
em->unref();
}
}
//------------------------------------------------------------------------------
// rfReceivedEmission() -- process returned RF Emission
//------------------------------------------------------------------------------
void RfSystem::rfReceivedEmission(Emission* const em, Antenna* const, LCreal raGain)
{
// Queue up emissions for receive() to process
if (em != 0 && isReceiverEnabled()) {
// Test to make sure the received emission is in-band before proceeding
if (affectsRfSystem(em)) {
// Pulses this radar frame (from emission)
//LCreal pulses = LCreal( em->getPulses() );
//if (pulses <= 0) pulses = 1.0f;
// Compute signal losses
// Basically, we're simulation Hannen's S/I equation from page 356 of his notes.
// Where I is N + J. J is noise from jamming.
// Receiver Loss affects the total I, so we have to wait until J is added to N in Radar.
LCreal losses = getRfSignalProcessLoss() * em->getAtmosphericAttenuationLoss() * em->getTransmitLoss();
if (losses < 1.0f) losses = 1.0f;
// Range loss
LCreal rl = em->getRangeLoss();
// Signal Equation (one way signal)
// Signal Equation (Part of equation 2-7)
// Signal (equation 3-3)
LCreal signal = em->getPower() * rl * raGain / losses;
// Noise Jammer -- add this signal to the total interferance signal (noise)
if (em->isECM()) {
// CGB part of the noise jamming equation says we're only affected by the ratio of the
// transmitter and receiver bandwidths.
// It's possible that we'll want to account for this in the signal calculation above.
// But, for now, it is sufficient right here.
jamSignal += (signal * getBandwidth() / em->getBandwidth());
}
// Save packet and signal for receive()
lcLock(packetLock);
if (np < MAX_EMISSIONS) {
em->ref();
packets[np] = em;
signals[np] = signal;
np++;
}
lcUnlock(packetLock);
}
}
}
