LO Phase Noise Report

The LO Phase Noise Report displays the effects of mixer LO noise on the system. Noise contributions are based on the mixer(s) having symmetrical upper and lower side-band power spectral density characteristics (additional information regarding SysCalc's SSB noise modeling can be found in Mathematical Definitions and Derivations).; therefore, the total mixer noise power is based on twice the equivalent SSB noise power in the bandwidth defined by the system. There are two report types as discussed below

Note — At least one mixer must have defined SSB noise characteristics for this report to be applicable. Additionally, this report is usually attached to the top-most System page in order to predict overall system performance.

Interference Report

An interfering signal offset from the desired signal will translate a mixer's LO sideband noise into the passband and thus desensitize a receiver. The Interference report type allows you to specify the offset of an interferer and to see the level required to cause a specific level of interference. For instance, in the report shown below, an interferer offset 25 kHz (at the system input) would need a signal strength of -65.7 dBm to cause MDS additional noise contribution by the mixer(s). This would, in affect, reduce the sensitivity by 3 dB since the channel noise would have increased by 3 dB. The same interferer is 54.5 dB above the sensitivity level (-120.2 dBm for this example) as shown in the Margin column. The interference power level is determined by each Mixer's SSB noise level and the filtering encounter by the interferer.

Note — The bandwidth 'behind' the mixer (defined by system filters or the probe) determines the frequency range over which a mixer's SSB noise characteristics is integrated. If this bandwidth is wider than twice the offset frequency defined in the report, the integration will fail. The report will indicate "No Data" under these conditions.

System Parameters

Project parameters are generally specified in the Project Properties dialog box; however, several of those parameter are made accessible on the Standard Report for convenience.

Demodulation Type	Displays the demodulation type selected in the Project Properties dialog box.
Sens. Loss	The loss in sensitivity (dB) due to inefficiencies in demodulator implementation.
Eb/No (S/N)	The margin (dB) above the effective noise floor (MDS) required to meet receiver sensitivity. For digital demodulation the margin is in terms of the bit-energy to noise-density ratio; otherwise, the report displays S/N (dB, Req’d) next to the field to allow entry of the required signal-to-noise ratio.
BER	The bit error rate performance required to meet receiver sensitivity. This field is only available for digital demodulation. BER is mathematically related to Eb/No according to the particular demodulation scheme chosen for the project. Entering a value in either of these fields causes the equivalent value to be computed and entered in the related field.
Es/Eb	The ratio of the energy per symbol to energy per bit. The effect of multiple bits per symbol must be included to relate sensitivity to MDS. This parameter is zero for all modulation schemes except QPSK and /4 DQPSK in which case the value is 3.01 dB
MDS	Minimum Discernible Signal - That input signal whose power level is equal to the noise power present at the system input. The input noise power is determined by the system bandwidth, source temperature and effective system noise temperature, i.e., KB(Ts+Te).
Sensitivity	The minimum system input level necessary to detect a signal. Sensitivity (dBm) = S/N (desired margin) + input loss + MDS.
Effective Noise Bandwidth	The effective system noise bandwidth (MHz) due to any filtering.

Interferer Group

Offset (kHz)	Specifies the interferer's offset from the desired frequency. This offset does not have to exactly match a Mixer's SSB profile; interpolation is used to estimate the SSB level when the offset falls inside of SSB profile. If the offset falls outside of the defined mixer SSB range, then the level at closest end-point of the definition is used. Offsets outside of a mixer's SSB profile should be avoided. Note — While one more than one interferer can be specified, each is treated on an independent basis.
Pwr (dBm)	The required interference power level required to contribute MDS additional noise.
Margin (dB)	The margin above the Sensitivity level.
Noise Contribution	The interference level can be adjusted relative to MDS by supplying a non-zero level (dB) in the edit control.

LO Modulation Report

The equivalent SSB power due to the composite power spectral density of all contributing mixers is computed in the LO Modulation report type. From the SSB power, other parameters such as Residual Phase, Residual FM, Hum and Noise and Error Vector Magnitude are displayed.

LO SSB Noise Integration Range

Start (kHz)	The start frequency for the SSB integration range. See Note 1
Stop (kHz)	The stop frequency for the SSB integration range. See Note 1
Equiv. SSB Pwr	The equivalent SSB power expressed in dBc relative to the LO level. The power is a function of the integration range and mixer(s) SSB power spectral density.
Residual Phase	The residual phase noise (radians rms) due to the total equivalent noise power. This calculation is an approximation and is valid for values < 1.

Note 1 - The integration range is applied to the SSB characteristics of each mixer in the system. The range is broken into segments corresponding to the mixer PDF being integrated. If the requested integration range extends beyond the mixer's PDF endpoints, SysCalc extends the corresponding PDF endpoint to include the range. A warning will be displayed in the dialog to indicate this situation. Care should be taken to ensure that the integration range is less than or equal the mixer's PDF range.

FM Post-Detection

For FM receivers, the Residual FM and Hum and Noise are computed as shown below. These parameters are more fully discussed in Mathematical Definitions and Derivations.

Deemphasis	Check to enable the application of a single-pole filter having a cutoff frequency defined by the associated time constant.
Time Constant	The time constant of the single pole deemphasis filtering (uS).
Residual FM	The Residual FM (Hz rms) due to twice the equivalent SSB noise and deemphasis filtering (if any). This calculation is an approximation and is valid for Residual Phase < 1.
Hum and Noise Ref Deviation	Reference frequency for the Hum and Noise calculations (8 kHz default).

Digital Characteristics

For all digital receiver, the LO Modulation report type displays the Error Vector Magnitude due to the mixer(s) total noise contributions.