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SAA4995WP

PANorama-IC (PAN-IC)

Philips Electronics 

Philips Semiconductors

PANorama-IC (PAN-IC)

Preliminary specification

SAA4995WP

Interpolation function

The interpolation for phase positions between the original

samples, is achieved with a variable phase delay filter with

10 taps for luminance signals and 4 taps for chrominance

signals. For luminance the PAN-IC supplies samples up to

32 MHz. For chrominance the PAN-IC supplies each

U and V samples with a data rate of 8 MHz (max).

Processing control in the PAN-IC

The compress factor (see Fig.4) at any position in the lines

is a function of the dynamically changing DTO-increment.

When DTOincr = 255, the sample rate is divided by 2; when

DTOincr = 0, the sample rate in the PAN-IC remains

unchanged; when DTOincr = −128, the sample rate is

doubled.

Control of number of samples per line

Three possibilities exist for the relationship between the

end of WEI and the required number of samples per line for

storage in the field memory:

• WEI negative edge coincides with the required last

sample in the line; standard operation.

• WEI negative edge is reached before the present last

sample in the line was required; extra dummy WE cycles

will be generated at the maximum rate (zoom factor 2)

to arrive at the required number of samples per line.

• The required number of samples per line is reached

before WEI negative edge; the DTO calculations will

continue until the required number of samples is

reached, but without generation of WE cycles.

The programmed number of samples per line is thus

always realized, independent of all other controls (unless

the line period becomes insufficient to store up to the last

sample in a line). When using odd/even sample

distribution, the programmed number of samples refers to

the number of samples in each data stream.

Consequently, the total number of samples is twice as

many.

There is an offset in the programmed number of samples

compared to the effective number of samples per line.

• Effective number of Y samples = 4 × (programmed

number of samples + 1)

• Effective number of UV samples = 1 × (programmed

number of samples + 1)

SECAM Y notch

A notch filter at the Y input of the PAN-IC can be switched

on. The purpose of this filter is to prevent artefacts from

scan velocity modulation with SECAM inputs. The notch

filter is an FIR filter with coefficients (−1 0 3 0 3 0 −1).

When fs = 16 MHz, the notch frequency is 4 MHz; the

maximum gain of the filter is +3 dB at 2 and 6 MHz.

Timing

The inputs are related to CL16 (half system clock). This

clock is used for reference in the PAN-IC from the CL16

pin. The system clock must have a fixed phase relationship

to the CL16 enable signal (one clock system).

Relationship of WE to video data

WE inputs and outputs may be used with either coincident

or advanced WE to video timing (see Fig.5). The advanced

WE to video timing is applicable to field memories, such as

the SAA4955TJ. The input and output WEs of the PAN-IC

can be programmed separately to either timing by the

in-phase and out-phase bits.

Odd/even sample distribution

The PAN-IC usually delivers a complete YUV data stream

to one receiving device, e.g. a field memory. Optionally, a

data stream can be split into odd and even samples, to be

received by two receiving devices.

The relationship between Y and UV samples is then

non-trivial (see Tables 1 to 4).

1997 Jun 10

6

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