March 1994

25

Philips Semiconductors

Objective specification

Integrated PAL and PAL/NTSC TV

processors

TDA8360; TDA8361; TDA8362

28. The amplitude response curve can be expressed as follows:

A(f) = 1 + K1

− cos (180 x f/3.1 MHz)

and is realised with a transversal peaking filter having delay sections of 160 ns each. In the ‘neutral’ setting K = 0

and in the minimum setting K =

−0.5.

The peaking signal amplifier is linear for 250 ns step input signals up to 50 IRE units. For higher amplitudes the

marginal gain is reduced. When the horizontal PLL is not synchronized (no signal present at the video input) the

peaking control voltage is pulled down by means of an internal current. This information can be used to detect

whether an input signal is available.

29. Slicing level independent of sync pulse amplitude.

30. The horizontal and vertical sync are stable while processing Copy Guard signals and signals with phase shifted sync

pulses (stretched tapes). Trick mode conditions of the VCR will also not disturb the synchronization. The value given

is the delay caused by the vertical sync pulse integrator. The integrator has been designed such that the vertical sync

is not disturbed for special anti-copy tapes with vertical sync pulses with an on/off time of 10/22

µs.

31. To obtain a good performance for both weak signal and VCR playback the time constant of the first control loop is

switched depending on the input signal condition. Therefore the circuit contains a noise detector and the time

constant is switched to ‘slow’ when excessive noise is present in the signal (only when the internal video signal is

selected, when the video switch is in the external mode the time constant is always ‘fast’). In the ‘fast’ mode during

the vertical retrace time the phase detector current is increased 50% so that phase errors due to head-switching of

the VCR are corrected as soon as possible.

When no video signal is received the time constant of the first loop is switched to ‘very slow’. This ensures a stable

OSD when the receiver is switched to a channel without transmitter.

The output current of the phase detector for the various conditions is shown in Table 2.

32. Picture shift can be obtained by means of a variable external load on the second phase detector. The control range

is

±2 µs; the required current for this phase shift is ±6 µA.

33. The vertical blanking pulse in the RGB outputs has a width of 22 or 17.5 lines (50 or 60 Hz system). The width of the

vertical sync pulse in the sandcastle pulse is 14 lines. This is to prevent a phase distortion on top of the picture due

to a timing modulation of the incoming flyback pulse.

34. The timing pulses for the vertical ramp generator are obtained from the horizontal oscillator via a divider circuit.

This divider circuit has 2 search modes of operation:

The ‘large window’ mode is switched on when the circuit is not synchronized or, when a non-standard signal is

received (the number of lines per frame in the 50 Hz mode is between 311 and 314 and in the 60 Hz mode between

261 and 264). In the search mode the divider can be triggered between line 244 and line 361 (approximately

45 to 64.5 Hz)

The ‘narrow window’ mode is switched on when more than 15 successive vertical sync pulses are detected in the

narrow window. When the circuit is in the standard mode and a vertical sync pulse is missing the retrace of the

vertical ramp generator is started at the end of the window. Consequently, the disturbance of the picture is very small.

The circuit will switch back to the search window when, for 6 successive vertical periods, no sync pulses are found

within the window.

35. This precorrection is intended to compensate for non-linearity of AC coupled vertical output stages. The value given

indicates the amplitude of the correction waveform with respect to the sawtooth amplitude.

36. At a chrominance input voltage (related to CVBS2) of 660 mV (p-p) (colour bar with 75% saturation i.e. burst signal

amplitude 300 mV (p-p)) the dynamic range of the ACC is +6 and

−20 dB.