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The redshifted 21‐cm signal from neutral hydrogen (H  i ) is an important future probe of the high‐redshift Universe. We have analysed  610 MHz  Giant Metrewave Radio Telescope (GMRT) observations towards detecting this signal from   z = 1.32 . The multi‐frequency angular power spectrum   C  ℓ (Δν)  is used to characterize the statistical properties of the background radiation across angular scales  ∼20  arcsec to 10 arcmin, and a frequency bandwidth of  7.5 MHz  with resolution  125 kHz . The measured   C  ℓ (Δν)  which ranges from 7 to  18 mK 2   is dominated by foregrounds, the expected H  i  signal   C  HI  ℓ  (Δν) ∼ 10 −6  to 10 −7  mK 2   is several orders of magnitude smaller and detecting this is a big challenge. The foregrounds, believed to originate from continuum sources, is expected to vary smoothly with  Δν  whereas the H  i  signal decorrelates within  ∼0.5 MHz , and this holds the promise of separating the two. For each ℓ, we use the interval  0.5 ≤Δν≤ 7.5 MHz  to fit a fourth‐order polynomial which is subtracted from the measured   C  ℓ (Δν)  to remove any smoothly varying component across the entire bandwidth  Δν≤ 7.5 MHz . The residual   C  ℓ (Δν) , we find, has an oscillatory pattern with amplitude and period, respectively,  ∼0.1 mK 2   and  Δν= 3 MHz  at the smallest ℓ value of 1476, and the amplitude and period decreasing with increasing ℓ. Applying a suitably chosen high pass filter, we are able to remove the residual oscillatory pattern for  ℓ= 1476  where the residual   C  ℓ (Δν)  is now consistent with zero at the 3σ noise level. Based on this we conclude that we have successfully removed the foregrounds at  ℓ= 1476  and the residuals are consistent with noise. We use this to place an upper limit on the H  i  signal whose amplitude is determined by , where  and  b  are the H  i  neutral fraction and the H  i  bias, respectively. A value of  greater than 7.95 would have been detected in our observation, and is therefore ruled out at the 3σ level. For comparison, studies of quasar absorption spectra indicate  which is  ∼330  times smaller than our upper limit. We have not succeeded in completely removing the residual oscillatory pattern, whose cause is presently unknown to us, for the larger ℓ values.

GMRT observation towards detecting the post‐reionization 21‐cm signal