East Asian VLBI Network (EAVN)

Brief Summary of Tianma65 Receiving System

Figure 5 shows a flow diagram of the VLBI receiving system in TMRT65. TMRT65 has the receivers for 8 frequency bands, L (1.4 GHz), S/X (2.3/8.4 GHz), C (6.7 GHz), X/Ka (8.4/31.0 GHz), Ku (15 GHz), K (22 GHz), and Q (43 GHz). The K- and Qband receivers are cooled HEMT receivers with dual circular polarizers. The observable frequency range and the typical receiver noise temperature are shown in Table 4. The total system noise temperatures at K- and Q-bands are typically 70 and 110 K, respectively. The RF signal is firstly down-converted to IF range of 4 – 12 GHz and it is transferred by optical fibers to the observing room, where the signal is further down-converted to 0 – 1024 MHz (actually in 10 – 512 MHz and 512 – 1024 MHz) at the input of BBCs.

Table 4: Frequency range and TRX of NRO45, Tianma65, VERA, and KVN receivers.
Band Frequency Range
[GHz]
TRXa
[K]
Polarization
Nobeyama
K 20 - 25 ~ 85 LCP/RCP
Q 42.5 - 44.5 ~ 111 LCP
Tianma
K 18.0 - 26.5 16 - 35 LCP/RCP
Q 39 - 47 35 - 50 LCP/RCP
VERA
K 21.5 - 23.8 30 - 50 LCP
Q 42.5 - 44.5 70 - 90 LCP
KVN
K 21.25 - 23.25 30 - 40 LCP/RCP
Q 42.11 - 44.11 70 - 80
(40 - 50 for Ulsan)
LCP/RCP
Figure 4: Flow diagram of signals from receiver to recorder for NRO45. Note that only the Q-band receiver is available for the EAVN 2018B open-use operation.



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EAVN ( East Asia VLBI Network )