KVN and VERA Array

Brief Summary of KVN Receiving System

The KVN quasi-optics are uniquely designed to observe 22, 43, 86 and 129 GHz band simultaneously (Han et al. 2008, 2013). Figure shows the layout of quasi-optics and receivers viewing from sub-reflector side. The quasi-optics system splits one signal from sub-reflector into four using three dichroic low-pass filters marked as LPF1, LPF2 and LPF3 in the Figure The split signals into four different frequency bands are guided to corresponding receivers.

Figures 8 shows a signal flows in KVN system. The 22, 43 and 86 GHz band receivers are cooled HEMT receivers and the 129 GHz band receiver is a SIS mixer receiver. All receivers receive dual-circular-polarization signals. Among eight signals (four dual-polarization signals), four signals selected by the IF selector are down-converted to the input frequency band of the sampler. The instantaneous bandwidth of the 1st IF of each receiver is limited to 2 GHz by the band-pass filter. The 1st IF signal is down-converted by BBCs to the sampler input frequency (512-1024 MHz) band.

Typical noise temperatures of K and Q bands are presented in Table 5. Since the calibration chopper is located before the quasi-optics as shown in Figure 7, the loss of quasi-optics contributes to receiver noise temperature instead of degrading antenna aperture efficiency. Therefore, the noise temperature in the table includes the contribution due to the quasi-optics losses.

The receiver noise temperatures of three stations are similar to each other except that the noise temperature of the Ulsan 43 GHz because of the different type of thermal isolator, which is used to reduce heat flow from the feed horn in room temperature stage to cryogenic cooled stage more effectively.

Figure 7:KVN multi-frequency receiving system (Han et al. 2008, 2013).
Figure 8:Flow diagram of signals from receiver to recorder for KVN (Oh et al. 2011).
Table 6:Digital filter mode for KaVA.
Mode Rate Num. BW/CH Freq. range Side
Name (Mbps) CH (MHz) CH (MHz) Band Note
GEO1K 1024 16 16 1 0 -16 U
2 32 -48 U
3 64 -80 U
4 96 - 112 U
5 128 - 144 U
6 160 - 176 U
7 192 - 208 U
8 224 - 240 U
9 256 - 272 U Target line (e.g. HO)
10 288 - 304 U
11 320 - 336 U
12 352 - 368 U
13 384 - 400 U
14 416 - 432 U
15 448 - 464 U
16 480 - 496 U
GEO1S 1024 16 16 1 112 - 128 L
2 128 - 144 U
3 144 - 160 L
4 160 - 176 U
5 176 - 192 L
6 192 - 208 U
7 208 - 224 L
8 224 - 240 U
9 240 - 256 L
10 256 - 272 U Target line (e.g. HO)
11 272 - 288 L
12 288 - 304 U
13 304 - 320 L
14 320 - 336 U
15 336 - 352 L
16 352 - 368 U
VERA7SIOS 1024 16 16 1 32 -48 U
2 64 -80 U
3 80 -96 L SiO (=1-0, $v$=2)
4 96 - 112 U
5 128 - 144 U
6 160 - 176 U
7 192 - 208 U
8 224 - 240 U
9 256 - 272 U
10 288 - 304 U
11 384 - 400 U SiO (=1-0, =1)
12 320 - 336 U
13 352 - 368 U
14 416 - 432 U
15 448 - 464 U
16 480 - 496 U
All channels are for A-Beam (VERA) and LCP (VERA/KVN). Mode names are tentative.
Total number of channels
Bandwidth per channel in MHz
Channel number
Filtered frequency range in the base band (MHz)
Side Band LSB/USB)
Example of spectral line setting

KASI logo image

KaVA ( KVN and VERA Array )